Audio sync problem that previously wasn't there

You already do it with the playback and Performer tracks, using sends to send it to the Performer. If you route it directly, you can’t hear it yourself unless you have Volume up, so that’s ok even if it’s different from the suggestion. So the Performer should hear all those channels, right?

This particular part confuses me. You mean to say that what you hear is not in sync with the readout of the transport bars+beats? That I wouldn’t be able to explain at all (unless you had “Constrain Delay Compensation” on).

I don’t think so. Also your project is just fine, it is obviously derived from the original template so I guess it also makes no sense to send you that as you have it already.
I admit I’m a bit clueless here. Set the “backing” track like the playback track (route to main out, use send to send to “To Performer”) then let me know: beeing connected, when you start transport, sound appears immediately but Transport bar readout is behind? Is Control Room off? Are you definately sure to not have “Constrain Delay Compensation” enabled (it’s a button on the top left of the arrangement Window)?
constrain.jpg