I have extensive experience with several Garmin GPS devices, ranging from old wearables, through hiking handhelds and bike computers. Generally, each of them reports GPS signal loss when for example going indoors or going through a tunnel. In that case another method of measuring speed and/or distance kicks in, if available on the device.
However, the FR735XT seems to behave differently. Whenever I go indoors and the watch has no access to GPS signal, it does not report the usual "Satellite lost". Instead it pretends it still has GPS signal and reports the last speed that was available when still outdoors. This obviously leads to fake distance accumulation when indoors, because when I get indoors, and signal is lost at 5 km/h, and then I stop moving, the watch still assumes that I'm moving at 5 km/h until I get outdoors to reaquire GPS signal.
Using a footpod makes no difference, although in the watch settings I have set it to use footpod when no GPS is available.
Anyone seeing similar phenomenon? I rarely use the watch indoors so I'm not sure if it's like this since day one or started with a firmware update.