I just noticed an issue in a recent update where I'll replace a page using a right click action in the page thumbnails pane and choose "replace page" and it doesn't update the page. So I save an individual page in illustrator as a pdf, then in a combined pdf choose to replace the page and choose the new file. No errors are reported, but the page doesn't actually get replaced. If I quit out of acrobat, reopen the file and try again, it then works. This is a huge issue as I've sent off files thinking the page got updated and then realized it didn't actually update the page. At least now I'm aware there's a bug and I'm manually making sure the page is getting updated.
Adobe Acrobat Pro DC Continuous Release Version 2021.001.20145