I believe it is possible that a poorly defined protocol could manage to be understood by the receiver better when at a shorter range. Maybe. But yeah, all my protocol info is third- or fourth-hand at this point, so I'm certain I don't have the all my timings set exactly the way they were defined. So if I can find a correlation between a specific protocol and range issues, hopefully I can come up with a fix.

Yes, I've now got all my protocols defaulting to a 50% duty cycle. A while back, I had the default set at 33%. I'm not sure that either default setting has made a huge impact; and, while I also see recommendations for anything from 25% to 50% in various places, I haven't yet found a protocol that requires a specific duty cycle.

I'm planning on setting the default back to 33%, as that is the LIRC's default as well...