Every one of those is probably the wrong polarity for the GT (unless you have the RJM specific Mission pedal). Please see the post at the top of this thread - you'll need to either rewire the pedal (a pretty easy job if the pedal is hand wired inside), or get a TRS cable that swaps the tip and ring.
I have a pair of EV-1 pedals on my GT16 board and they operate correctly when wired with a standard TRS. I also have tested a pair of EV-2 pedals and confirmed they work as well with a standard TRS.
@Soren Kelly : for troubleshooting, I recommend starting at the beginning with three easy-to-miss items. It sounds like you've tested this already but I have gotten these wrong occasionally when setting up a board for a customer, and it makes me laugh every time when I realize I've missed them.
(1) As RJM noted, some TRS cables are intentionally wired to swap the ring and tip, and they're not always clearly marked. If you have a multimeter or tester, verify that you're using a standard TRS.
(2) Fractal EXP pedals have ins/outs for volume pedal use, and a separate EXP jack. Verify you're using the EXP jack.
(3) On the MMGT, double check that you're plugged into the Expression Pedal inputs, and not the External Switch Inputs.
If those seem OK, take a look in the MMGT editor at the "Global" tab. In the center row, just right of the middle, there is an "Expression Pedal" group. Double click on Global Settings / Expression Pedals to verify that each Expression Pedal is set to correct values. Here's a screen grab of my EXP1, which is a Fractal EV-1 pedal. Different values for Taper, Min / Max Value will change the behavior of the pedal. I'm using the default values, so if yours differ, try resetting them as shown.
If that all seems as expected, take a look at your Presets tab. In the lower left corner, you'll see options for Exp Pedal Overrides. If there are any boxes checked, take a look at them to see how they're set.
If that doesn't sort it, ping me and I'll send you my .rjm sysex file. It's for a GT16, but I can verify that it's working with EV pedals plugged into EXP 1 and 2, using standard TRS cables. I'm seeing the expected full range of values from each pedal. You can back up your current .rjm file, load mine, change the model to GT22 (that setting is on the Global tab, top left), and test it in place to see if you're observing the expected expression pedal sweep. If that isn't it, we'll need RJM to provide guidance.