This has happened a few times so far in the last few days of testing, once using a 38400 baud rate.
Herelink works at 57600 baud rate and mavlink protocol. You may check your serial settings in your autopilot.
Does the FRX Pro conflict with the Herelink?
I googled and found that FRX Pro works on 900MHz, while Herelink works on 2.4GHz. So I think they won’t interfere each other.