I'm having some HST problems with my 2015 L45 that sounds similar to what you recently experienced. The tractor lurches when moving in reverse -- like no movement for a few seconds, then a lurch backwards, then no movement for a couple seconds again. Repeats over and over. I've been tolerating it for a couple weeks now, but suddenly I no longer have any forward movement. Reverse still behaves with the lurch but pressing the pedal in the forward direction has no result, other than revving the engine when Auto Throttle Advance is enabled (but that is mechanically connected between the pedal and the engine throttle). What is most odd is the tractor was working fine with forward movement two weeks prior. I parked it and didn't touch it until Saturday and after starting it the forward did not work at all. Seems strange that the problem would occur while the tractor was parked.
Using the IntelliPanel test mode shows the voltages change in both pedal directions so I assumed the pedal sensor is good based on that. So I've been thinking I'm going to have to tear the HST apart to find the problem, but this thread has given me hope. You also had good readings on the pedal voltage test yet the pedal sensor was still bad.
I have the WSM for this tractor and measured the resistance between the 4 pins on the pedal sensor and 2 of the three measurements check out but the third measurement does not. The WSM claims it should be between 0 and 1 KOhms but I'm seeing it stay between 0.9 and 1.5 KOhms. So I'm hopeful that this is the problem. I have not yet had a chance to test the Fwd and Rev swash plate sensor resistances, as they are tucked in tight under the floor.
I'm curious if you happened to isolate which of the sensors was bad, since you stated you replaced both. Did you ever try one sensor replacement at a time? Also, did you ever test the sensor resistance with an ohm-meter?