Drone not sending MISSION_REQUEST_INT after initial MISSION_COUNT

Hi everyone. I’ve run into an issue where I am able to send a MISSION_COUNT messages (as per the mission protocol) to a drone, but the drone does not respond with the necessary MISSION_REQUEST_INT in order to process each waypoint. This is working fine in the SITL, and other messages such as COMMAND_LONG and PARAM_SET are taken onboard by the drone. Does anyone have any ideas? Thanks in advance!

Why did you not tell which fw version are you using?

I believe it is the latest Arducopter fw (4.3.1?). I don’t get any messages telling me to update it anyway.

Strangely it lets me upload missions through something like QGC but not from the missions I send. The packets look identical, even in the headers. Not sure what could cause the MISSION_COUNT to be completely ignored.