But generally speaking most devices will default chest strap when it is worn and connected provided that you have a message telling you that a connection has been made. What device are you referring too?
On my last activity I had some HR drop outs - rate going down from ~170 to ~140bpm while holding the same pace. My suggestion was, that the strap was not connected anymore and the watch (FR935) recorded the HR on the wrist. Therefore such drop outs would be nothing new ...
The fit2tcx list a device called "hrm4_run". So I assume the strap was connected. I also had a look at at the battery level yesterday and the battery was pretty much empty. Maybe that caused the drop outs.
in your fit2tcx data the text "hrm4_run" should be there multiple times when there is an ANT+ drop and a reconnect
the Fit File Repair Tool is easier to view such drops and transitions
Yes, there are several entries with "hrm4_run", will check that out with the "Fit File Repair Tool" too - since I'm on a Mac this could take a while ;)
...the watch would inform you when the voltage becomes too low :)
