I'm using InDesign 2021. I have been using the option at the bottom the Pages window ("edit page size") to change the size of my document from US Letter to A4 as I offer both sizes of printables in my shop. I noticed tonight that this sizing is being buggy. I went to change my Letter size doc to an A4 size, but A4 was already checked. The rulers confirmed my doc was in Letter. I then tried to change it, but no selections held from that menu. Finally, I just went to the "adjust layout" menu option and changed it that way.

Is this an InDesign bug, or some kind of user error? All my pages are consistent with one single master.