Previously, structures containing custom loot chests could be saved and loaded using structure blocks to generate different loot every time the same structure was loaded. With 20w22a this stopped working, as the chests now generate completely empty. It is possible that this bug arose in an earlier snapshot, though I have not confirmed that. Using /data reveals that the loot table tag is lost upon loading - so the issue cannot be with the generation of the loot that occurs upon opening of the chests. The issue is also not with the way the structures are saved, since structures that were saved in previous versions worked then and now no longer.

Note that I have not been using custom loot tables, so that is also not a relevant variable.