Transmission issue?

I changed the motor in my vehicle listed above 35i XDrive. Everything went smoothly, the only thing out of the norm I had to do was shim the starter. I get everything put back together, start the engine, put it in reverse and it just revs, then goes back to park by itself. Same think if I put it in drive. It revs and goes back to park. Then the transmission malfunction comes on the idrive. When I scan with ISTA I get 4 codes. Ratio Monitoring Clutch B, Clutch A+B, Clutch B+C, and All Clutches. When I run through the diagnostics it has me do oil line adjustment, then the gear ratio service function. I get to were the condition for the fault is read out and it jumps right to replace transmission. I had zero issues with my transmission before the motor swap, is there something I’m missing the motor fires up and runs, there is a couple codes in the motor as well. O2 sensor and a valvetronic motor issue, but I can take care of them, but I can not figure this transmission issue now out. The vehicle did sit for about 4 months before I got the engine and put it in. The old engine spun a rod bearing and cracked the crank. So it went from running and driving to sitting for 4 months, until I got a different motor. Any help with this issue would be greatly appreciated.

Thanks

Justin