@freestepper After completing all challenges, I have 2 main problems with them.
1. Bugs:
- Enemies not spawning (especially bad in Wolf challenges, where you have to kill all of them in a specific way)
- Random explosions (Templebrough Wolf is particularly bad, more often then not map starts with some jars eploding and killing enemies, thus you have to restart if you want gold)
- Game doesn't correctly register the way you kill enemies (headshots and indirect kills). In Wenlocan and Callevah Wolf challenge the best way to kill them is fire arrows or dropping them from ledges. Everything else is not reliable. In Odin Cave Raven challenge, where you have to assassinate everyone from air, apparentely if you jump on the enemy, lying on the ground after sleeping arrow, it doesn't count as air kill. You have to wait untill the guy wakes up and is standing. You also cannot jump on crouching enemy for some reason.
- AI irratic behavior (suicide, death by enemy archers, death by enemies archers expoding things etc). In Raven challenges sometimes enemies grow eyes on their backs.
You don't need much skill to complete these challenges, but sheer luck and pray that all enemies spawn and you will not run in bugs.
2. It just not interesting and fun. I had no problems with trying different gear and abilities, but the constant need to keep track of all conditions was really frustrating. You don't kill enemies the most efficient way, you fill the ticks. This sucks fun even during Bear challenges, which were my favorite.
So basically, the idea was interesting, but the implementation is just bad. Maybe they should have play better with different modifiers.
Before getting into these, I thought Raven challenges would be the most frustrating, because how stealth is broken in the game. But Wolf challenges were the worst and they need fixes badly.

All of this could be avoided, if they made the quest condition to just participate in River Raid like in Community challenge, but noooo. Foreign supplies were canceled month ago. It's just not many people were engaged in highly repeatable River Raids. Now that you have a quest to complete, a lot of players noticed this problem. And it backfired.
And we cannot get Egghead Bow. And horse/boat/swim sprint doesn't work on PC if you activate Heidrun Slam.
At this point, is anyone surprised?
Paris, here we come.

Turned out, it was Avast antivirus. You need to add Valhalla.exe to exceptions, then the game launches. It seems, this problem is mostly for people in Eastern Europe. Weird.

@TheNorfolkian Somebody at Ubisoft Support: "Finally a worthy opponent, our battle will be legendary!"

1. Predator quest happens every third day.
2. Predator quest doesn't work outside England.
3. Predator quest doesn't work when scaling is on.

How much time is needed to fix this problem? Every time I launch this game I meet a message saying how awesome and incredible is Ubisoft. Time to prove it.

@torfinr Reda still has the same contracts, and max amount of opals per week is 120 (if community challenge is completed, which is not always the case). This means you can only buy one item per week. Mounts and birds are ridiculously expensive, I think.

@ubi-borealis Thank you for clearing things out. I hope in any future possible River Raids in Ireland or France we'll be able to loot things without any problems.
May I also be so bold and kindly ask you to take to development team the suggestion to increase River Raids rewards from small runes to big ones? They are very scarce in the game and that would make the players more interested in RR.

I just saw patchnotes for 1.3.1 Update (tomorrow):

• Jomsviking Hall can be upgraded to Level 4-5, allowing players to hire Jomsviking of Level 4-5, respectively.  
  • Jomsviking of higher rank can carry more rations and do more damage to enemies. 

https://discussions.ubisoft.com/topic/107263/assassin-s-creed-valhalla-title-update-1-3-1?lang=en-US

@alphagoose46219 Inscription on Eyvor's grave in Vinland: She/He raided too much.

Still nothing? It's been almost 3 months.
Funny how fishing exploit was "fixed" in a week.

@TheNorfolkian Yeah, just feeling a little bit salty after this news about cutting down old games online features. Sorry to mislead you
This whole situation reminds me of infamous fish bug that took too long to fix.

@azullFR It happens on PC too, not PS exclusive. Noticed it trying to hop on my horse during predator quest.

@pesto So that's what it was... I was wondering why I got this quest the first day of 1.6.0 and never after switching nigthmare scaling off.
Still getting Bonnie and Clyde, but not every day now.

@TheNorfolkian Somebody at Ubisoft Support: "Finally a worthy opponent, our battle will be legendary!"

1. Predator quest happens every third day.
2. Predator quest doesn't work outside England.
3. Predator quest doesn't work when scaling is on.

How much time is needed to fix this problem? Every time I launch this game I meet a message saying how awesome and incredible is Ubisoft. Time to prove it.

@Randelia I am a bit confused, by "today" you mean August 2, the day of weelkly reset, right?
Predator quest happens every third day. Before Update 1.5.1 it was bugged with a workaround to set default scaling. This workaround was broken in Update 1.5.1 when predator quest disappeared for everybody, no matter the difficulty or scaling. Now it's back to 1.5.0 situation, which is an improvement, but the bug is still not fixed.

@TheNorfolkian Yep, they pretty much reverted animal quest to 1.5.0.

@Randelia Predator quest not working on higher difficulties was mentioned in this thread several times along with it not working in Ireland and Frankia at all.

@Ubi-Keo It was partially fixed. Animal quest was not available on Aesir difficulty, for example, but became available after I changed my difficulty to Saga.
@TheNorfolkian Try to change difficulty, worked for me.

@TheNorfolkian Yeah, just feeling a little bit salty after this news about cutting down old games online features. Sorry to mislead you
This whole situation reminds me of infamous fish bug that took too long to fix.

@TheNorfolkian Sarcastic. We don't have much info on Infinity yet.

@Et4hiel Don't worry, Assassin's Creed Infinity will have paid patches as a part of live service. After all, Ubisoft is always open for new possibilities, like NFT.
At this point it is clear that this bug is caused by "kill the animal" quest. So there are 3 ways to resolve this problem.

1. Fix the bug.
2. Temporarily replace animal quest with something else (not that there is a great variety of them, but still) while fixing the bug.
3. Investigate the problem until everybody forgets about it (after all, those helix credits don't sell themselves).

Still nothing? It's been almost 3 months.
Funny how fishing exploit was "fixed" in a week.