Why can I assign myself both webinar and session

[Prosem]

Hello,

I have this assigning problem here.

My account is a Pro type. I use webinar for a quite a long time.

Recently, my client ask me to add breakout session in the webinar.

After some research, I found I have to buy zoom session to have this feature.

Now my webinar is already been created and there are already registrants. I need to concert the webinar to session.

After purchase the session, I cannot assign my account with session.

The odd thing is, other account can, but not for my account which is the owner.

Appreciated if any one could spot the problem, and help to solve the problem

Thanks.