Elements not synchronized - why?

I’m using Syncthing for four weeks now - I’ve setup deveral devices (3x Windows11, 1 Tablet, 1 Smartphone, 2xMX Linux and 1 Raspberry Pi (Raspi OS lite). I’m syncing several folders and generally everything works very well.

Now I got a problem I can’t figure out what is happening. I’m syncing a folder “Userguides” among others between “Geekcom Win 11” and the raspi. Suddenly some 20 elements show up as “not synchronized”. I removed these subfolders with their elements and the folders on both systems were up-to-date and synced.

Now I added one subfolder (=Einhell) together with one file inside. And now I got the same problem as before. I add 2 screenshots (one of each system) to show the message:

This is the Geekcom webinterface:

This is the “missing” element:

What might the problem be? I’ve no idea where to look at.

Support