Has anyone who has built, uses, or used a Cross Machine LH upper - Stag Arms LH BCG combo, had any fail to feed, or fail to lock back issues, while not firing suppressed, that they could share.

I recently rebuilt an existing, and perfectly fine running RH SBR upper into a LH SBR upper (semi auto only), because of un burnt powder-ejection port-face issues while suppressed.

The only difference are the new gas tube (BCM), the new Cross upper receiver, and the new Stag BCG.

BGC is GTG,,, gas key is attached as it should.
No gas leaks past the rings, and remember, this is the same barrel and gas block that were on the old upper receiver.

Nothing hanging up while working the charging handle.

I haven't heard anything on the errornet bad about Cross uppers, but am wondering if there is something I don't know about a Cross/Stag combo that is taboo .  

FWIW, this is a dedicated suppressed gun, and it runs fine (not just fine; like a sewing machine) suppressed.
I'd just like it to feed and lock back un-suppressed, if I so chose to run it that way

Thanks in advance,,,
Jay