Unable to Arm from RC after Enabling MAVLink on TELEM 2

After enabling MAVLink on TELEM 2 I can’t seem to arm from the transmitter. I have been arming from QGC and using the kill switch on land to work around this, but does anyone have a clue as to whether I did something wrong? This has happened on two platforms now. During checkouts without the payload installed arming and disarming from the transmitter worked, but after mounting the payload and configuring MAVLink I can only do it through QGC. The first time I was really confused, but after the second I noticed the sequence of events that caused the change. It’s possible I changed something I shouldn’t have while troubleshooting the MAVLink connection, though I would have had to do the same thing both times.