Aura Won't sort into collections

[MJLee]

I have a strange problem. I have an ancient and well-belowed Aura One. Suddenly when sideloading from Calibre it won't import Collection metadata. I've tried doing it manually but it won't 'take' as in it shows when I add it in Calibre but then when I try to open it in my reader it's not sorted into any Collection. Most of my books are not bought from Kobo store, quite a lot of it is fanfic. I tried to remove all books without a Collection but when i import them again, same problem.

Anyone encountered a similar problem and how do I solve it? I don't want to buy a new. I love the big screen size (with my bad eyes it's a necessity).

Edit: Sometimes it will update content but it doesn't help and not sure how I can trigger that.