Installed Alpha 4 over version 3.1.33 and had current version of Deskscape11 v.10.93 running.
In the last version of Fences 3.1.33, the snapshot would be black if Deskscape was running. Now, with Fences 4 Alpha, there is simply no indication a snapshot was even taken.
Update: Snapshot also does not work with Fences 4 Alpha even on Win11 x64 which never had *any* version of Deskscape installed (so it is unrelated to Deskscape).
Windows 11, x64 OS.