I was able to flag down your case. Support should be getting back to you shortly.
It sounds like your sustain pedal might be the wrong polarity. Try using an add like MIDI Wrench to see if MIDI is making it from your pedal at all.
The easiest way to tell if your pedal is the wrong polarity for you keyboard is to play some notes using an app like SampleTank. If the notes sustain before you press the pedal and stop when you hold the pedal, this would indicate your sustain pedal might be the wrong polarity for this MIDI keyboard.
This is a free app on the Apple App Store.
https://apps.apple.com/us/app/midi-wrench/id589243566Note* Most expression pedals require a 1/4" TRS cable. If they don't include an attached cable, using a 1/4" TS cable can result in switch-like behavior from your expression pedal.