HX Stomp IR weirdness

Recently picked up an HX Stomp for a couple of gigs where I need certain tones for one or two songs.

I've got it set up with Path A being my Electric side, using a standard amp and cab

Path B has an IR loader on it, with a Faux-Acoustic IR I've used to ages.

When I programme the setting with HX edit, it all works fine.  If I navigate to another preset, and then go back - Path A still work fine, but the IR doesn't produce any sound. If I switch off the IR block, Path B passes signal, if I change the IR to an Empty spot, it passes signal. It's just when I navigate away from the preset and back to it does it stop working with the IR

Is there something obvious I'm missing?

Update: Found a work-around - if I put 3 blocks of +12dB Gain after it the IR works properly...

This surely can't be right, can it?

Gulliver said:

Update: Found a work-around - if I put 3 blocks of +12dB Gain after it the IR works properly...

This surely can't be right, can it?

Look in the IR block settings for anything that might be inadvertently dropping the signal level?

TimmyO said:

Gulliver said:

Update: Found a work-around - if I put 3 blocks of +12dB Gain after it the IR works properly...

This surely can't be right, can it?

Look in the IR block settings for anything that might be inadvertently dropping the signal level?

Or in the path split block that's doing the same? 

TimmyO said:

Gulliver said:

Update: Found a work-around - if I put 3 blocks of +12dB Gain after it the IR works properly...

This surely can't be right, can it?

Look in the IR block settings for anything that might be inadvertently dropping the signal level?

There's nothing I can see - it was working perfectly when I imported the IR into HX edit, I hit save and it works fine - it's only when I navigate to another preset and then back that it acts weirdly...

Gulliver said:

TimmyO said:

Gulliver said:

Update: Found a work-around - if I put 3 blocks of +12dB Gain after it the IR works properly...

This surely can't be right, can it?

Look in the IR block settings for anything that might be inadvertently dropping the signal level?

There's nothing I can see - it was working perfectly when I imported the IR into HX edit, I hit save and it works fine - it's only when I navigate to another preset and then back that it acts weirdly...

Does sound odd. 
Paging HX experts @rossyamaha  @JohnCordy  in case they have any bright ideas? 

The only thing really that springs to mind is a firmware thing.