Cannot create New Snapshot with MOD layer

It is not possible to create a new snapshot from a Zynthian configuration that consists of one MOD layer. All I get is the moving Zynthian logo, but no configuration/ snapshot is saved. Creating new snapshots that do not contain an MOD layer works.
The strange thing is that I can update the default snapshot - for example after adding a synth layer.
Apart from the moving Zynthian logo I cannot see any error messages in the output of journalctrl -u zynthian.

What build are you using? What branch?

2104-stable with all latest updates.