Unfortunatly, I have the same problem too. Helix LT fm 3.15. I have a lot of my presets with snapshots. Some parameters of effects has snapshots contro. When I connect my helix to PC, and working with presets, I see the same message and other mesage, where write that data is lost etc.
If I save this preset, I can have bad preset with bad data. For example, I can switch snapshot, but footswitch doesn't light up. Etc.
This problem is appeared when I work with presets with snapshots only.
Line6, ask you fix this problem!!! Please.