Don't know if this has come up before, but I wanted to save someone else a few hours of troubleshooting if possible.
If you use DashWare to overlay video from another camera source (GoPro in my case) the default profile has a problem with the data import fields.
The short version is the GPS data field has multiple options separated by a semicolon, which DashWare then uses as a data separator and after this point all the data fields get off, so while GPS speed will work, g-force, RPM, gear, etc wont (which is very frustrating).
To fix the problem, open up the data field profile, and make a clone of the Harry's Lap Timer Pro profile (the original is locked from editing).
Next unselect everything except for 'comma' as a data separator and save the profile with a new name.
Next time you are adding a data file, select the new data profile, and all the gauges will work properly.
I will post screen shots of this shortly.