Hi Mike,
Each Action Button is linked to a different microflow, and the permissions on these two mf was set for both user roles 'Beheer' and 'Gebruiker'. I have changed it and saved&deployed my app again, but unfortunately both action Buttons are still visible for the user role 'Gebruiker'.
I have made a screenshot of both MF below.
MF for Tenders
MF for Bids