Is there a reason my bookmarks are no longer defaulting to the previously used folder, rather they keep defaulting to the same folder over and over?

When you go to bookmark something, it usually automatically saves to the last bookmark folder you saved something to, but withing the last couple of weeks, everything keeps defaulting to the same folder. Now if I have multiple tabs I want to save to the same folder, I have to keep searching for that particular folder multiple times in a row rather than Firefox keeping that as the current default. I haven't changed any settings lately, and I can't find any way to fix this