Re-scheduled meetings limited to 45 minutes

We are having the next problem:

If a user has a meeting with a duration of one or more hours, and the session is rescheduled (they usually use the outlook complement for scheduling and rescheduling meetings), appears a message indicating that they have a limit of 45 minutes, as if they had a Basic Licence.

This situation started today, and it has happened to two users.

In both cases they have a Business Licence.

¿What could be the problem?