I see some people reported problems with dropping HR monitors in v4.44.0.26618. I don't think these have been resolved in 4.45.1.28048.
My case is a HR monitor from a Garmin watch connected on ANT. I am used to the production TDA dropping that every once in a while, but it always returns after a few seconds. The 4.45.1.28048 beta has a nicer message (it actually says the HR monitor dropped, production version says something dropped, but does not mention HR monitor), but it does not pick it up again. I have not found any way to re-connect the HR monitor during the ride. Only stopping the ride, exiting the beta TDA, and newly broadcasting the HR monitor does it.