I've only just read this post - I know, slow!
But I noticed after the last upgrade that there was no volume on some of my patches. Not all, just some.
And then I realised that, for some reason, Helix had decided to put a volume block at the beginning, set for a pedal at 0%! Remove it, and bingo, all there.
What it appears is that original Line 6 patches seem to have grown this extra block, but not mine or other third party presets.
Weird, but there you go.
And I'm sure someone's already pointed this out; if so, sorry