Thank you so much for the response! It's great to see that your project is still active. The convenience alone it adds is second to none... just need to work out a few more kinks.
With 0.4.4 I tried doing just that (setting an 03 filter) but while the filter worked fine when connected to USB I could never get it to return anything over BLE, ensuring that only Serial1 was connected (I noticed the interoperability between Serial and Serial1).
After spending some time reviewing all the sketch code I was left with the impression that it should just be working. I'll check out 0.4.5 today and report back.