A few users have reported that the CmisSync icon stops appearing in the task bar a few days after having installed FreeFileSync.

A bug in FreeFileSync makes it sometimes remove the permissions of your C:\Users\<youruser>\ folder. These corrupted permissions prevent CmisSync from starting correctly.

The solution is to fix the FreeFileSync corruption by restoring the permissions. The steps should be something like this:

Step 1: Right-click on C:\Users, choose Properties:

Step 2: In the Security tab, click Advanced:

Step 3: In the Owner tab, click Edit:

Step 4: Select your user, enable the Replace owner on subcontainers and objects checkbox, and press OK.

Step 5: Reboot the computer.