engine knocking after transmission fluid was added to engine oil

If the transmission fluid washed all the motor oil off the surface of one or more crankshaft connecting rod bearings, that might produce a knock once the bearing had gone without motor oil long enough that it caused some wear and began to create a space in between the bearing and crankshaft throw, thus causing a banging or knocking but that should have taken some time.
How long was this transmission fluid in there?
If it was just less than an hour or so, I don't see why it would have caused this.
Now if it was left in there like all winter perhaps.