[SOLVED] 09/17/2025 beta update resolved this issue, and vdf file now exceeds the 1234kb limit that was causing it to clear itself.

[old]
So I apparently, in my meticulous and tedious organization of my library, with many collections, HAVE FOUND! the limits of localconfig.vdf in the userdata/user/config folder.

So the file updates in real time, as you add games to collections.
I will add them, and refresh the file explorer page, to view the updated file size. I will watch it got from 1,232 to 1,233 to 1,234 and then as I add a few titles to a collection, instead of rolling to 1,235kb, it will instead drop to 1,202kb, effectively WIPING the non-steam collection associations, resulting in all non steam games being uncategorized on restart.

PLEASE Fix this
Thank You :)