Thanks for chiming in. Today’s bug report UE-80016 pretty much stole my thunder and added it crashes during a “Shipping” build, even worse. So as my detective work concluded it’s not a legacy problem(thank goodness) but a real 4.23 bug it would seem. No other problems noted(I have seen) with a Development build and exe. Just the missing Materials.
Anyone else seeing it, please add your vote to bug UE-80016.