TEC 5.8 Updated Calendar View issues

Hello,

I just updated TEC 5.7 > 5.8 and upgraded to the new Calendar Views.
Now, on my calendar months view, several functions don’t work anymore.
This calendar URL is: /agenda/

Heaver Events Bar: Previous month
– Clicking the left arrow doesn’t show the previous month, current month still displayed.
– The URL is changed into /agenda/(/?:month|mois)/: weird, is that normal?

Heaver Events Bar: Search and List/Month/Day links
– Don’t return the expected views, current month still displayed
– URL is still /agenda/(/?:month|mois)/

Heaver Events Bar: Date picker
– Choosing a previous month works
– URL is /agenda/(/?:month|mois)/2021-06/
– To be noticed: the Date picker dropdown is not showing on my site until i disable all plugins, probably a conflict somewhere, no error in the console

I cleared the caches, rebuilt the permalinks, disabled all other plugins, swapped to the regular 2021 theme, same issues.

The issues disappear if i disabled the TEC “Use upgraded calendar views” option

Thanks for your help!