you need to import activities from garmin and on activity screen (insode activity details where graphs are) add custom data like epoc, you will need to reprocess imported previously activities, after rhat the epoc graph will show the data
/writing feom a phone, later will explain it better but you can find a forum topoc how to import garmin specific data (vo2, epoc, aero eff etc) inside an actovity
its on bottom of activity screen β fields β search etc
edit: sry it is in custom and not fields