I thought the settings were right, as it works properly in an Audiofront (I use 2 Quattro).
To be sure the problem is with the Xtone Pro, have you ever done the same test in another vst host, daw, etc?
Yes, it shows like this in Mainstage and the small app MIDI monitor as well. Without any gigs coming up, I can handle the discomfort, but it would be nice to sort it out!
Do you know if the AudioFront has some software under the hood to smooth things out? Or could a script fill in the gaps?
Have you contacted the Xtone Pro developers?
I don’t understand what you mean… I you add am AudioFront device to your setup it will work properly 
Seriously, XTONE people should fix this, it shouldn’t be a big deal…
Did you try this?
XTONE Pro has 3 MIDI command modes, press A+B switch to mode 1, press A+C to mode 2, press B+C to mode 3. When the switch is successful, mode 1 blinking green, mode 2 blinking blue, mode 3 blinking red.
Different APP may use different command modes, If you find an abnormality when using foot switch, you should try switching to the other two control modes.
Mode 1，For JamUp, BIAS FX, AmpKit+, etc. Most other software effects also work for this mode.
Thanks, Paul. Yes, I tried them all but to no avail!
Yes, in their Facebook group. I hope they will reply soon, otherwise I will contact them through their website. At least one other person confirmed the behaviour on his device, so I’m not alone!
This jumped cc values do not make any sense.
Tell them you discovered the problem when trying to use it with gig Performer
Yes, the Midi Expression includes standalone and vst app where you can draw curves and all that stuff but it works of course with Midi Expression hardware, as there is no software in the expression pedal to store parameters. So you need using the Audiofront until Xsonic provides a solution.
This is what they say:
Hello guys! This is due to the sampling frequency of the expression pedal by XTONE, which is designed to avoid the control delay of the expression pedal. In the same time, the accuracy of the value change corresponding to the fast and slow stepping on the expression pedal is different, but this will not affect the effect of Wah or Mod.
Does anybody understand their line of thought?
??? 
!!! 
This seems at least to affect what you want to do as you could notice it!
You should ask them to answer in a precise way the question “how to have a normal progression of values (+1 or -1 increment)” by attaching a screenshot of the MIDI monitoring window.
2 Likes
Yep - they’re trying to avoid acknowledging that their system has a bug!
Ask them why the AudioFront is able to handle the pedal properly.
Yes, any unexpensive micro-controller can sample a pedal level as quick as necessary, it is unbelievable!
I just wanted to chime in that I have tried several different Behringer FCB1010 pedal controllers and they ALL skipped some CC numbers particularly in the lowest range (0 to 20 range). I can hear it, and Midi monitor proves it. I still can use the FCB1010 just fine for some coarse volume control in middle range when I need it (like a swell volume pedal on Hammond).
But to actually get a “completely smooth fade from/to zero” I added one extra stand alone pedal, the Behringer FCV100 combined with MIdi Solutions Pedal Controller. (The way I set it up it is like adding a third pedal to the existing FCB1010 using the midi in on the FCB1010). That adds the ability to get a completely smooth fade from/to zero when I need it.
If it is related to the pots if the FCB1020, you can rescale the volume by setting 20 to be zero. This kind of rescale should not be eared.
Just a wild guess… Have you calibrated your pedals?
If not, follow the steps in the link - maybe it helps?
https://en.wikibooks.org/wiki/Behringer_FCB1010_MIDI_Pedal#Expression_Pedals
@schamass
Thx, but yes, I had tried calibration.
(I think calibration is really just making sure pedal range goes all the way down to zero, and all the way up to 127).
I went to some effort to test multiple FCB1010, and while they all go full range (from 0 to 127), they all skipped midi CC.
Calbration just did not seem to have any effect on the skipping issue at all.
So while I do find FCB1010 is still generally useful, my experience is there is no way to go to/from zero without hearing the jumps.