On my system the problem was caused by files in /var/lib/snapd/apparmor/profiles/ not being generated.
Part of the snaps installed on my system had a corresponding file in /var/lib/snapd/apparmor/profiles/ and those snaps did work.
Other snaps did not have a file in /var/lib/snapd/apparmor/profiles/ and did not work.
To fix this I: 1. ran "snap refresh core --beta" 2. rebooted my system on an Ubuntu kernel (it usually runs a mainline kernel)
Now all snaps have a corresponding file in /var/lib/snapd/apparmor/profiles/ and all snaps do run.
For now I do not know which one of 1. or 2. fixed the problem.
On my system the problem was caused by files in /var/lib/ snapd/apparmor/ profiles/ not being generated.
Part of the snaps installed on my system had a corresponding file in /var/lib/ snapd/apparmor/ profiles/ and those snaps did work.
Other snaps did not have a file in /var/lib/ snapd/apparmor/ profiles/ and did not work.
To fix this I:
1. ran "snap refresh core --beta"
2. rebooted my system on an Ubuntu kernel (it usually runs a mainline kernel)
Now all snaps have a corresponding file in /var/lib/ snapd/apparmor/ profiles/ and all snaps do run.
For now I do not know which one of 1. or 2. fixed the problem.