Here the debug info:

          - 04.02.2022 10:43:58
525CE798X - UI-Language: de-DE
525CE7B7X - FencesUI Start - /saswelcome 
525CE815X - FencesUI End   - /saswelcome 
525CE854X - UI-Language: de-DE
525CE873X - FencesUI Start - /fixpermissions 
525CE8D1X - FencesUI End   - /fixpermissions 
525CEA28X - FencesUI End   - /verifyintegrety 
525CEA57X - UI-Language: de-DE
525CEB03X - UI-Language: de-DE
525CEB22X - FencesUI Start - /updateconfig 
525CEB22X - FencesUI End   - /updateconfig 
525D1C35X - UI-Language: de-DE
525D1C44X - FencesUI Start - /saswelcome 
525D1C83X - FencesUI End   - /saswelcome 
525D2E36X - UI-Language: de-DE
525D2E55X - FencesUI Start - /saswelcome 
525D2E84X - FencesUI End   - /saswelcome 
525E1059X - UI-Language: de-DE
525E1068X - FencesUI Start - 
525E367EX - FencesUI End   - 
525E4582X - UI-Language: de-DE
525E4592X - FencesUI Start - /saswelcome 
525E45C1X - FencesUI End   - /saswelcome 
525E562CX - UI-Language: de-DE
525E564BX - FencesUI Start - /saswelcome 
525E567AX - FencesUI End   - /saswelcome 
525E62BFX - UI-Language: de-DE
525E62CEX - FencesUI Start - /saswelcome 
525E62FDX - FencesUI End   - /saswelcome 
525EBFB3X - UI-Language: de-DE

Hello, I checked it - the Fences aren't locked.
I locked them and unlocked again - it still doesn't work.
Thanks in advance

Sorry, didn't use the reply button - answers below, still doesn't work

Hi Basj,
thank you, I followed the steps and it works now

But the new version is a little bit buggy compared to Fences 3 - when I activate the folding of Fences, nothing happens. I need to doubleclick on the title bar to do it. Once it is done, it works fine. And sometimes dragging with right mouse button needs two attempts to have the option to create a Fence.
All in all: It works now, I'm happy.