Disable alarm does not work on Samsung S9

I want to disable my 'work' alarm when my calendar has an event 'holiday'.

The task 'Cancel alarm' only opens the alarm app on my phone, but does not cancel it. Makes no difference which mode (disable current, by label, any). I have a Samsung Galaxy S9 with Android 8.0, alarm app v7.0.92.4.

PS: The task 'Set alarm' actually does work.

PS2: also plugin 'ClockTask' wont disable an alarm.