Hi,
I have a similar experience on my RPi2 based LE installations:
Mounting my timecapsule with a .mount-file has always worked but since I upgraded to LE 11, I can’t get it to work any longer.
I have done clean installs with LE 9, 10 an 11, always with the same .mount file. On 9 & 10 it works, on 11 it doesn’t.
If I update 9->10->11, same thing.
Maybe support for the required sec=ntlm and/or vers=1.0 options has been dropped from kernel 6 onwards?
For now, I’ll stay on LE10.