We are still looking into this issue, but there's a workaround posted earlier in this thread,
Please try the steps here to see if this helps with your issue.
Thank you
I found another workaround that worked for me:
1. Run Uplay as administrator
2. Settings: Disable Cloud save
3. Restart computer
4. Run Far cry 5 as administrator
5. Cry that your save can't be brought back
Bam i got my game to work but only because i disable the cloud save, so i lost my progress but now i can play. hopes this helps.