After the latest roundcube update, it seems that the actions 'Save as Event', 'Save as Task', 'Add a Note' on emails are not available i.e. they are greyed out.
Strangely, if you open the email in a new (standalone) window, then the actions are available. See screenshots for both cases.
Could it be a bug in the front-end code?
ii pykolab 0.8.23-0~kolab1 all
ii roundcubemail 1:1.5.3-1~kolab3 all
{F9779885}
{F9779891}
Update 12-Apr-2023: I installed Kolab on Debian 10 from scratch to check if something broke in my setup. The issue is still present on a clean install, it must have been caused by one of the latest (Feb/Mar 2023) Roundcubemail updates in Kolab.