In an old world made one or two betas back,I did the /locate bastionremnants command,so when I tped to the bastion's coordinates the whole thing was made of update blocks.also,the bastions were in newly loaded chunks.

how to reproduce:

*1.*load up a older world

2./locate a bastionremnant

3.the remnant will be made of update! blocks

EDIT: I noticed that the remnant was "fixed",meaning that it had a magma spawner,however no loot in the treasure chests

EDIT EDIT:this used to be an rtx world