If you are someone that does a lot of track intervals on the track or on the treadmill and want exact and accurate recording this will affect you!
The only way to edit splits currently in the app is to export the tcx file then modify it in some sort of xml program (I use xml notepad) then manually upload the file into garmin.
There is a major bug with this garmin connect import process. If you import a file that you have edited in tcx it works great the FIRST time you do it but if you delete the activity from garmin (meaning you made a mistake in your interval corrections because sometimes it's easy to mess up when editing in xml or because we are all human) ...usually you would go back to the tcx file and edit it and try to upload it with the new changes. Now it never updates the changes...it tells you it uploaded the file but the activity uploaded is the same as the first one you uploaded without the new changes...it's like they have cashed in memory the file you initially uploaded and no matter how many changes you make to the file and reupload you will still get the same result...the initial bad file you uploaded.
I tried updating the ID on the file which seems to be the date and that still did not work.
I tried resaving the file under a new name and uploading that file and that also did not work.
BUMMER! This is a HUGE pain in the A#@#@#@# since I am a bit anal about keeping my log recordings to the detail.