Unable to add one more Planner TAB to a new Teams Group

I am not able to add a new Planner Tab for a Teams Group.
I receive this error : 

When I try to do it with Microsoft Planner Web interface I see that a lot of Teams Groups ( Office 365 groups ) are missing :

I guess that those 2 problems are related

All groups are visible in Office 365 Admin page:

Any idea how to fix this ?

Thanks in advance,
Danny