I have created several different digital menu boards in After Effects. For some reason now the majority of the files will open, but they don't show anything in the composition window. I can't see anything, it's all grey with an outline box of the composition. Some of them show up if I leave the file open long enough. I used to not have any problems with them. Does anyone else have this problem or know how to fix it?
Have you upgraded to AE2018 >15.00? Adobe has dropped support for some of the older Codecs (especially many QT codecs) so it may be that your source footage isn't compatible any more.
Reverting to AE2018 15.00 will still allow you to use these older codecs - but you do have to put up with a few bugs that were fixed in 15.1.