MacBook Screen Freeze

When I use Zwift on my MacBook with a usb-c lead connected to hdmi out. The screen intermittently freezes for long periods.

MacBook Pro (13-inch, 2020, Four Thunderbolt 3 ports)
Processor - 2.3 GHz Quad-Core Intel Core i7
Memory - 32 GB 3733 MHz LPDDR4X
Graphics - Intel Iris Plus Graphics 1536 MB

If I use a separate usb-c connector for the ANT+ and the HDMI lead I can unplug the HDMI and then the screen goes black for about 10-15 seconds on both TV and MacBook, then unfreezes (on the MacBook) and I plug the HDMI back in and continue; until the next freeze in (x) minutes.

This happens every time I use Zwift without fail. It does not affect any other programs therefore it is certainly a problem with Zwift and not with my MacBook or the MacOS (this is a problem that has spanned MacOS updates).

A number of Zwift updates ago - I used Zwift without any issues on the same MacBook, same screen, same leads, same internet router and network adapters etc. This problem was introduced by one of the previous updates - however, I cannot say when it started.

This is VERY frustrating as it ruins the ergonomics of my training setup (I spent quite a lot setting it up).