Hi,
I had the same issue last year. The problem is the Helix does not support midi "Running status" (the "status byte" is not send by the FC-300 if it's the same as the previous midi message, only the new value is sent).
The idea is to force the FC-300 to not activate the "Running status" by sending 2 differents midi message at the same time.
You have to be in "Patch Mode" on the FC-300, and program 2 "patch" (midi stream) to send the pedal value to 2 differents midi CC or midi Channel (for exemple 1 midi message on the CC 1 of the channel 1, to control the Helix, and another on CC1 but on channel 8, which correspond to nothing). Like that, for each pedal position, the FC-300 will sent 2 messages and can't activate "Running status).
Hope this help