This is utterly pointless but...
Been playing fine (well minus the other issues that I have posted on here and will never be fixed) and have completed DLC 1 and 2.
Joseph took one hour to allocate disk space and then started to download and install the meagre 12gb file. This install has taken another hour.
To answer the inevitable questions:
What type of drive format are you using?
NTFS
2. How much free space is on that drive? 1.90TB
3. Is it possible to try another drive and see if that helps? Given all the other game files are on this drive and DLC 1 and 2 downloaded and installed within minutes, no.
Huge thanks to Forum Mods for making it feel like our bugreps meant something.
I know very well low hanging fruit is picked first in fixes, but there's so much rotten fruit here.
I am disappointed that this forum is just a façade that bears no fruit on what really gets fixed, but thanks again Forum Ubi mods for the cheerful and positive output you provided.
