I'm
not saying you should change this setting. I was just saying that, if ever this setting
has been changed at some point in the past, then it
could be the reason why you can't access old revisions now.
From your first answer to my suggestion, I understand you never changed this setting (am I wrong ?). Then It must be something else. I have no idea what could cause your issue.
If you really want to try to uncompress all the files and change the compression setting to 0, which currently does not seem to be the solution :
find 7zip; download and install it. then in windows file manager, select the .gz files, right click, in 7zip submenu, select extract here. You may need to
fix file permissions of the uncompressed files.
As usual before playing with an application's files, make a backup and be sure you know how to restore this backup, and you are actually able to restore all the directories to the exact state they are today. You may have to fix file permissions after restoring.