Activities disappeared from activity subgrid

Hi Dynamics experts,

Question: yesterday I came to the realization that some activity types disappeared (a week ago it was still there) from the + button in the activity subgrid (its in Dutch), the following activity types suddenly went missing: Task, Phonecall and Recurring Appointment. The rest is there:

On the associated view they still exist:

Could someone give me pointers as to how to fix this or where it possibly went wrong?

It happened on both sandbox and production (possibly after a deploy on last friday, which included customizations to the activity entity, task entity and appointment entity, but not the recurring appointment and phonecall entities).

I already tried the following:

- reset the sitemap

- restore the activity entity

- re-adding the subgrid

- checked the relations of task, recurring appointment and phonecall

- check if the notes pane still has these activity types (yes it does)

- some other things i forgot..

Help would be greatly appreciated!

Regards,

Joseph