See this thread - https://forums.garmin.com/outdoor-recreation/outdoor-recreation/f/fenix-6-series/230759/heat-acclimation-for-fenix-6-and-edge-830.
heat acclimation on Edge 830 does not transfer to GC app in training status. GC only uses Fenix 6 for heat acclimation. Suspect GC app issue.