Power data in GPX files

Hi

Garmin VIRB Edit does not seem to always recognize GPX files. For instance I record an exercise with iPhone for an indoor ride with power data (Garmin Vector 2S powermeter) and then I try to import the GPX file in Virb Edit but the power data is not seen. OR: I record an indoor ride with Trainer Road Windows desktop app then convert the TCX file (Trainer Road just gives me a TCX file) to GPX using the TCX Converter utility (freeware available on Internet to download). Again, Virb Edit does not see the power data in the GPX file.

I surely can manually generate the GPX data (e.g., write it letter-by-letter in Notepad :) but I couldn't find enough clear information about the structure of the GPX file so its contents is recognizable by Virb Edit. Especially about power data (i.e., watts). Any suggestions ?

Regards
Mihai