Guests joined recurring meeting ended up in a waiting room but host could not see them

Hello, we have a business account and have used it to host our courses since 2020.

Today for the first time, guests in a recurring meeting were joining the session that was already opened by the host with guests inside... but some of the guests who were joining the same meeting were stuck in the waiting room and the host could not see them.
We ended up creating a new session in a different account so everybody could join.

has this ever happened to someone?
thank you