Possible bug - Monuments

[Northern20]

Playing as Brandenburg, after conquering Marienburg from Danzig the monument went from level 1 to 0. I know that normally when they get conquered that monuments will downgrade 1 level but I thought that they werent supposed to go below level 1, did this get changed?

edit

latest version and no mods, all dlc except origins

 

[grotaclas]

I can reproduce this, but it seems to be new. I can't find anything in the changelog, so it might be a bug