I just tried it with a Sony DVD remote laying around, and it works perfectly! I suspect my problem has something to do with the fact that the buttons on the universal remote need to be programmed. Ah well, at least the Flirc works exactly as I hoped!
I recently bought a Flirc USB for my Macbook Pro v10.12.6 with software v3.25.3 and firmware v4.9.3 (both are the most recent Flirc versions). The Flirc software says that I have successfully recorded my keys to my remote, but I can't get the remote to use the keys. The remote still works and I haven't ever had a problem with it so I'm hoping someone can help troubleshoot this issue. I've also tried clearing the configuration multiple times and I've no luck.