Internal players in rekordbox not showing up

Hi there,
have a problem with the internal players in rekordbox 5 & 6. Both are installed in the latest version on my mac (big sur) and in both versions of rekordbox wether player 1, player 2 or the simple player are not showing up. On the space where normally the players are located, is nothing but a black box with no content and I cannot load any tracks into the decks.

Not sure if, this depends on my rekordbox settings or not... 
Any ideas? Thank you!