creating new Tasks list fails

in Nextcloud Tasks i can no longer create new lists –
neither in the web interface
nor on devices synced to my Nextcloud
[Apple Reminders on iOS]

it has worked fine for years
but stopped working after upgrading to Hub 8
[if i am not mistaken]

after clicking ‘Add List…’
i can type a name for a new Tasks list.
but nothing happens when hitting ENTER
or clicking the arrow button to the right
of the chosen list name

any advice
?

THANKS

Nextcloud Hub 8 (29.0.2)
hosted at all-inkl.com
OCCWeb app installed