Had a ton of trouble getting my 2011 to go into programming mode for the keyless remote, which was weird as I have previously done it with no problems in the past. After trying the same thing over and over I thought about it a bit, reread the manual, and saw how part of it involving removing the key from the ignition cylinder when done. A few years ago, the key sensor that detects of the key is in the ignition failed and stuck closed (a pretty common Subaru problem) so I had unplugged it and had no problems since then. Once I plugged that sensor back in I could successfully enter programming mode and program the remotes, though at the end I had to unplug it to “finish” the process, and I left it unplugged because of all of the various problems a broken sensor like that causes. I replaced my keyless entry unit because I was getting intermittent TPMS disconnections and all the sensors are new, and the car usually wouldn’t respond to the remote unlock when remote start was active. Yet to repair the TPMS sensors but the remote start issue was fixed.
speaking of remote start, recently the immobilized module in the remote start system was failing to broadcast the signal to disable the ecu lock during remote start. I removed the offending box, disassembled it, tested the pins and circuit board for continuity, then soaked it in MAF cleaner. After reassembling it works good as new, but we will see how long that lasts, hopefully through the winter at least. Seems to be another common Subaru problem, but at least, like with the key sensor, there are free fixes for them