Could you please put the Joplin-1.0.178-x86_64.Appimage into the releases/download/v1.0.178 directory on GitHub?
Although the Linux install / update script detects that 1.0.178 is the latest appimage version there is a 404 Not Found when it tries to wget the new appimage. Sadly this happens AFTER the script has deleted the previous version.
Can confirm that I have the same issue with pdfs being empty on both Win10 and Linux Mint 19.3.
Also on Linux Mint it appears that, despite the settings box being ticked, Joplin does not start minimised. Admittedly it was a manual install of the appimage as the upgrade script cannot wget the appimage (see above)
EDIT: The not starting minimised issue appears to have a been related to the failed install rather than Joplin itself - Please ignore.
It seems that the app image download file on Github is now named Joplin-1.0.178.Appimage rather than Joplin-1.0.178-x86_64.Appimage. if you edit the script to remove -x86_64 from the wget line it will work.
it appears on Github that the script has been fixed and is waiting to be merged.