Sync Client: selective sync of sub-folder not working on 1 of 2 machines (option is greyed out)

The setup:
I am using the Seafile Sync Client 7.0.4 on two different machines. One is my laptop (Win10) and the other is my desktop PC (also Win10). On both machines I am logged into the same account which is on a Seafile Pro server. Both clients language is set to german.

Now my problem:
I am trying to selectively sync a sub-folder from one of my libraries. On the desktop PC this is possible and looks similar to how it should according to the seafile help of “Selective Sync Sub-folders” (EDIT: can’t upload a second picture nor post a link to the help page …), meaning I can click on the option “Sync this folder”/“Diesen Ordner synchronisieren” and it does what it should. But on my laptop, when I try the exact same thing, the option “Sync this folder” is greyed out (see Picture_2, “Diesen Ordner synchronisieren” is the german version for “Sync this folder”).

So far I couldn’t find any relevant difference between these two machines. Does anyone have an idea what’s the cause for the greyed out option? Or maybe, did anyone have the same problem and found a solution?

If you need any additional information to solve this, I will gladly provide it.