First, check on tablet that the file is displayed in the cloud section of the Save File dialog on the computer. If so, the file has successfully been uploaded to the cloud.
Next, quit FMT on your computer, wait a minute or so for it to sync then check again on the tablet.
If that doesn’t work, trying logging out of Steam Cloud on the tablet and back in again.
If you’re still having difficulty, create a new thread on our bugs forum: https://community.sigames.com/forum/593-football-manager-touch-2018-bugs-forum/