This works in our tables and in other areas but not within the Calendar itself. And likewise with Tooltips which do not appear either, nor do Dynamic Titles respectfully.
Any advice appreciated! Probably just being the usual moron and missing something simple...
Click on the Calendar Component within the page then click Dynamic Attributes and select Calendar / Tooltips, select your Binding and voila Tooltips are displayed. We were trying to use Dynamic Attributes / Display / Tooltip (which doesn't work).
Still can't get the Dynamic Class working though but thought I'd mention the above to save further investigation of that side.
The event element doesn't support the class toggle, maybe I can make it work in the future. As a workaround you can use the Class Name binding and use event.extendedProps.concluded == 1 ? 'linethrough' : '' as the expression.