Thanks for your input and excellent suggestions. Yes, I'd been through the steps you mention as part of the trouble shooting process, and yes it happened with creating new, as well as editing existing presets.
The good news is that after a couple of sessions attempting to discover what was causing the issue, it now seems to have cleared up, although I'm not sure what particular step cleared the problem! I suspect it was something to do with the pedals rather than the Helix. Maybe I had initially overlooked something during troubleshooting.
Anyway, back to playing instead of tearing my hair out. Thanks again....