Can you please make it possible for the user to be a Support Specialist and an Account Manager at the same time?

After trying to add a certain user as a Manager to a client, I couldn't find them in the list. I added their name in the Managers list, system even filled all info for me, and after that user lost all rights to manage support cases and disappeared from the Support Specialists list.

So...

If user is registered as a Support Specialist, they can't be assigned as a Manager to a certain client.

If user is registered as an Account Manager, they can't manage with support cases.

We have a person who need to do both using the same account.

Can you please consider this feature?