I recently ran an Ultra and my watch accidentally went into emergency mode which caused it to save & close down my race. I was able to restart my watch a few mins later using the same course, but this means i now have 2 activities. I have using FIT file tools to merge into1 file and this was successful. I then deleted both 1 and 2 activities out of Garmin Connect & tried to upload the single merged file. No errors are reported, however, Garmin connect is not able to upload, in fact, nothing happens. I also tried using GOTOES to merge and check the activity files as well as the merged file, all came back without error.
If you are able to merge & add to my activities it would be greatly appreciated.