Hello!
I face the problems reported here: [SOLVED] Roller skiing workouts
Answers there claim .fit file has sport type ‘generic’, which I can confirm. Based on that thread discussion I get the impression Polar integration uses .fit files as message format. I found that doubtful, since .fit seems to be Garmin specified. Also this Polar sync thread talks about using the Polar accesslink-api. Since rollerski (both freestyle and classic) is supported in there ( Polar AccessLink API ) I must ask why the mapping doesn’t work in Intervals?