iCloud sync stuck for iMac

I work on my MacBook Pro and my iMac. I try to access my files in iCloud from both devices. However, the sync on iMac is often stuck.

For example, I edited some files on my MacBook and I made sure that the changes had been synchronized in iCloud. I can access the changes from my iPad and iPhone with no problem. But when I try to access those files from iMac, I can't because the sync is stuck as the pic shows. It is stuck because it is like this for 2 hours. This happened to me very often. Sometimes, restarting my iMac solved the problem. Do I really need to do this every time?