I have not had an issue with mine, from the outdoor tri wing or the myriad of other sensors I have. I figure my max distance is 75 feet though, but through steel doors. I'm crossing my fingers it hold up and I don't experience your issue.
Since yours went from working to sporadic, something has changed, may be increased interference. Obvious things are to change the batteries in the outdoor unit, but I'm guessing you already did that.