Ubuntu-mate-welcome broken (after apt upgrade)

Installed UM for Raspberry Pi 400 64 bit. Overall experience is great - a very, very fast O/S - several times faster than the standard Ubuntu Desktop!! And Mates gives me all the features I want in a desktop. Great distro!

BUT...
The Ubuntu Mate Welcome app - and Boutique - is broken. When I try to launch it from a terminal I get:

internal error, please report: running "ubuntu-mate-welcome" failed: cannot find installed snap "ubuntu-mate-welcome" at revision 578: missing file /snap/ubuntu-mate-welcome/578/meta/snap.yaml

It may well have been working in the original distro - but I didn't try it and it didn't launch automatically. But it is definitely broken after "apt upgrade".

I used apt to uninstall the ubuntu-mate-welcome package and reinstall it - but it is still broken.

I have now also tried to remove the package with snap and reinstall it, and when I try to reinstall it I get:

  • Run install hook of "ubuntu-mate-welcome" snap if present (run hook "install": cannot open seccomp filter /var/lib/snapd/seccomp/bpf//snap.ubuntu-mate-welcome.hook.install.bin: Permission denied)

Same issue with software boutique

It might be that it is broken for the Pi 400