We have noticed that this issue is impacting custom UI across all native platforms, not just macOS. It is being caused by the meeting status callback not being properly invoked when joining or starting a meeting with custom UI mode enabled.
We do not have any updates on this yet, but I assure you that we are treating this as a high priority issue and are working on getting it resolved ASAP.
We have published a new version of the SDK that has resolved this issue. Please let me know if you are still seeing any issues after downloading it from the Marketplace. Note that this version has replaced the previous 5.7.1 version of the SDK that was published last week.