2012 Mustang M/T tach issue?

Did a 2012 Mustang M/T, using a customer supplied ProStart and Evo-All bypass. W2W install, soldered, ground in kick panel.

Car has been back once already, customer stated that in the morning (cold start) the vehicle runs for less than 3 minutes then shuts down. He loses the Ready Mode indicator on his LCD remote, which was telling me that the parking brake, hood or brake switch signal was either active or lost.

Disconnected the outputs for these functions from the bypass module, and connected directly to the vehicles brake switch and parking brake, and installed a hood pin.

Now, the vehicle still shuts down after a few minutes in the morning, but the remote starter does not exit Ready Mode. He has to remote start it about 3-4 times in order for it to run longer than the few minutes (have the starter set to 15 min runtime).

Called in today, and someone from tech stated that they have seen issues with cold start tach signals from these vehicles, and suggested that I use the cam sensor as my tach reference.

My question is, has anyone experienced this tach issue with the newer Mustangs, and if so, did you have to go to the cam sensor to remedy the issue?