The wild card in all of this is that it is YOUR Performance and we only have the few details you have given.
We doubt that unplugging and replugging the instrument is he ONLY way to fix the problem, but it does give us one big clue, it is something that is reset by rebooting. Meaning it is something that is being changed (edited) due to parameter manipulation. More than that we can only guess. You'd need to provide a bit more information about your Performance.

If the same thing happens on a factory Performance, that would also give us something to go on. But if it only happens in your Performance, then that tells us it is something in the programming.

Let us know what exactly you are doing. I've never heard of this happening... so confidence is high that it is something easily fixable by proper use of the instrument. It is totally possible that a control message is telling Parts 1 and 2 to reduce volume, and since this would leave the Rhythm Part sounding, and would also be reset by the drastic move of unplugging and replugging the instrument (not recommended, by the way, without powering down first), this could be the first thing to investigate. You don't mention anything else connected to the MX (for example, pedals, or via USB a computer, a laptop, an iOS device, perhaps via MIDI an external keyboard) so we cannot begin to make any guesses without first eliminating any and all of these, one by one.

Is your Performance a LAYER? A SPLIT?

Thanks for your fast reply!

I am only using the keys basically, the only thing plugged in is the sustain pedal ( and left and right jacks of course). This is going to my Behringer XR16 desk

What I changed was the factory performance 001 ... all I changed here was the part 1 and 2 instruments, the rhythm sounds, panning and volume.

I then saved it as performance 001 and overwrote what was there in the first place.

For my other performances I stayed with editing the parts on 001 and then saved as performance 002, overwriting those setups.

My MX is at work so I cant give you all the parameters right now. But I can do that later on.

The sound seems to fade slowly and then all of sudden stop so turning it back on resets the sound to the level I had at a soundcheck for example... could it be a loose connection?

.... performances are mostly layered. A couple are split.

The sound seems to fade slowly and then all of sudden stop so turning it back on resets the sound to the level I had at a soundcheck for example... could it be a loose connection?

Unlikely, because you stated that the "rhythm pattern continues", a loose connection would disrupt all audio. You also stated that "Changing the panning back to center have not made a difference the problem still persists." So again unlikely a loose connection on one channel's jack or the other.

Please, when you can, provide the additional details.

Hello again!

OK so I have my keyboard with me and I have saved the settings to USB via the utility/file setting.
Sorry for being so daft ... but I have no idea how to open it on my Mac.
I have searched online and have not found a solution. The file extension saved is .X5A
Can you advise please..
Thanks

Looks like the latest version was not installed. So I have downloaded and installed it.
I am entering the performances again manually and will see if this new version and reboot make a difference.

Hey there Bad Mister 🙂

What additional details do I need to send you? Shall I send you the X5A file?

I trialled it all again last night after rebooting but the same thing happened. Not as drastic this time though.
I'm thinking it could also be a PA problem. I am using the behringer XR16.

If by looking at my X5A file you can tell me more then I will send it across to you.
Cheers

The computer cannot read a .X5A file, that's an All data file for the MX. It contains data specific to the .X5A.

There is nothing that could imagine that would be learned from your file. Since you realize it may indeed with your PA system, I think that is much more likely, based on the info you've provided. I'm not saying that the MX could not be at fault, it is just that it would be beyond all odds that it would cease to function in the way you describe. If it were to break that way, that would be one for the record books. 🙂

What happens when you press SELECT (after your 'fade out' problem has occurred) and dial up Performance 003 or 111? Is it 'all there'?
What I was thinking was that you may have turned the Sustain Parameter down by mistake - remember, the knobs function in 3 different ways, depending on which of the Key Function lights is illuminated....And if the LINK light was on, it would have turned down the sounds that appear to have been 'fading' - after the decay segment of their (edited) envelopes had passed...
So calling up a different Performance would be a test. Is that sound 'all there?' -
Another test would be calling up Performance 101 after your 001 and 002 (which is basically 001) was selected and began to fade...and THEN calling up Performance 001 again. Is it back?