Last week I've migrated from OTRS 4.0.15 to 5.0.6, I thought everything went fine until I noticed that when I'm in a ticket and
hover with my mouse over the dropdown menu People or the Miscellaneous menu option that this isn't working

the dropdown menu isn't showing ?
I don't have any errors in my logs, did I perhaps forget something or is there some parameter not activated ?
Regards,
Niels