RP 500 group Release version - 6.1.7-450056, can not enter Multiconference Meetings

Good morning, we have Polycom realpresence 500 equipment, registered in a Huawei Telepresence infrastructure, and after the update to the latest Software Release version - 6.1.7-450056, we can not enter Multionference Meetings, the point-to-point calls if they work,
what is the solution? How can I make a Downgrade? Thank you very much OSPO