Ensure that the controller is soldered and connected completely. Reflow the solder. Replace if necessary.
Also, check out this really good video from 1up Keyboards that explains how and when to do a bridge: https://youtu.be/N5IivDkrp6U
Check the following:
- diode is in the correct orientation
- diode is soldered completely
- hot swap socket is completely soldered
- the switch posts are not bent
- verify that the keymap isn't using a special key at that position (firmwares like QMK sometimes use non-standard/custom keycodes that cannot be detected)
These guides focus on the hardware. Most keyboards sold on KeyHive use QMK firmware and the following resources are the most helpful:
The TRRS cable should not be removed while either side is connected to USB. The reason is that the TRRS wires pass power and data over to the second half, and connecting/disconnecting can potentially apply power to a pin that should not be powered.
Some sync issues can be resolved easily by resetting the EEPROM memory, disconnecting from USB, and then connecting again.