Using the new code I did not see any guidecam timeouts yesterday night. Today I inadvertedly reverted to the old code (doing a fresh git pull) and ended up with two guidecam timeouts during the first two hours of operation. I re-enabled the new code and until now haven't see any further guidecam timeouts.
This appears to explain the guide timeout problem I've seen for the past several days. Being that I'm using macOS, is it advised that I downgrade to 3.5.4, wait for an updated stable/beta release for macOS (soon?), or is it possible for me to build myself for macOS?