Grafana doesn't show all the Teams created and is not possible to add users to some of them

We are using Grafana 6.5.3 on CentOS 7

From the web interface we can’t see all the teams, so is not possible to add new members to some of them.
We know that the teams are there and actually if we try to add one of them to a folder permission we can see it correctly.

Do you have any idea about this strange UI behavior?
Is there another (easy) way to add a user to one or more teams?

Thanks a lot in advance.