I have seen blogs and posts about this error dating back a ways, but the "fix" of disabling "Protected View" and "Enhanced Security" is busy work that does nothing to alleviate this intermittent problem.
Our firm uses Adobe Acrobat Standard 2017 and I have found the issue most prevalent if pdfs are combined and then you realize a doc is missing, so X out, try to combine again and now its all grey.
Wondering if ther eis any new informaiton on resolving this issue.
This is the lovely grey screen 😞
This was a supposed fix in Jan 2021 that did not work.