I’ve tried this achievement multiple times throughout different times in the story line to no avail. I’ve played ~ 130 hours and tried it about 20 times. A save icon appears after I slice 150 m but no achievement pops.
I completed Skadi’s Hobby by sliding 150m (did about 170m for good measure) and the achievement didn’t trigger. I’ve tried restarting game and reloading a save - to no avail.
One of the wealths has respawned in Vinland after recent update and is now unlootable. Its the only collectible I need to the completionist achievement.