Teams Approvals for guest users

I've created a Inventory Sharepoint List and if a certain status is shown in the status column, a Approval request is sent out with the help of a Flow, to a recipient given within another column. This works fine for people in the organisation and the item get's updated accordingly. 

But I have a problem: 

Due to the nature of my organisation (non profit/sports club) some people are only registered as guest users within Teams. When I put their Email in the recipient column, the Flow works fine and sends them an approval request through the Teams App, but instead of giving them the opportunity to deny or accept the Approval Request, they get no option at all. 

No option to accept or deny the request is displayed for a guest user

I have read that this is happening because the person is only added as a guest user through Teams and should instead be added through Azure AD as a external user. 

Does anybody know if this would work?