I can not create an (flexicontent-) menue item

It is an local Testarea works with wamp64 Joomla is 3.10 flexicontent 4.1.5 .Template is in Backend isis and frontend shaper_helixultimate - Standard   PHP 8.0.28
If i create a menu item, i can choose: flexicontent - category ( for examle) it is okay.
if i want choose a category, then open the list, but there is no button, to confirm my selection. 
Is this my issue, can i also configure this or is it a bug?
 

you have a js bug this need to load in modal but seems broken
update to last 3.X and update lnguage file

Thanks for the answer,
I tried that, unfortunately it didn't work.
I've completely reinstalled it now and it works. Thank you

thanks for return