I was on Version 8.3 (20799) Stacks -
Today I updated to 8.4! Bin that I just saw that Foundry accordions and tabs were not working correctly in last version. Only just tested those.
Now on Version 8.4 (20812) Stacks 4.0.3 (4795) - ignored plugin warnings and all seems good. Im doing some rebel work today so will see what if anything breaks.