Strangely, the gif file was finally there on the PC after a few hours, and now I tried again to export gif and the same problem.. the file created can be seen only on the phone and not on the PC.... what a strange and annoying bug =\
I uninstalled and re-installing but it didn't help
Browsing the forum I found other people experiencing the same issue, and not only with the Cinemagraph app, but couldn't find a solution...