Background colors. missing randomly in PDFs

I had a mysterious issue with Adobe Acrobat Pro, where some backgrounds were missing from some random PDFs when I opened them in the APP, but not when I viewed them in my BROWSER.

After talking with Adobe, I found that the reason was an accessibility issue. “Replace Document Colors” was somehow checked in Preferences, and I just had to uncheck it.

I have no idea how that happened, or why it only caused a problem with occasional PDFs. Just wanted to share, in case anyone else has that problem.

Amy