First Ironman and activity won't show up in Garmin Connect but shows on my watch. I have tried manually importing using Garmin Express and continually get the import error. Can someone repair my fit file?

I completed my very first Ironman this past weekend and recorded the journey using the multisport activity. Everything recorded and saved on my watch which I am able to see in its entirety. However, it will not upload to Garmin connect. Need help.