Invisible text in Adobe Acrobat Pro DC
I work on combining a lot of different documents for proposal books in an answer to an RFP. Every now and then (randomly), some pages of the document - random letters will go invisible. They won't be gone, I say invisible because I found a hack, where I can select all the text, make it bold and then unbold, and all the letters show back up. Sometimes the text will come back all by itself in a day or two, but usually don't wait that long.
Here are a couple of screenshots I took from my recent book that had this issue:


This is a really big pain for larger books and when it's crunch time to get it submitted and I have to go back over every page and make sure all the right words/letters are there. I've struggled to find this issue anywhere online, I've uninstalled and reinstalled it, and tried looking through a Preflight report to no avail. If anyone has any advice/suggestions - I'd be happy to try!
Thanks.
-Matt
