@hotellonely That’s very strange to hear! I was on beta, and then I read about your problem and how it went away after reverting to the stable release, so before even running the test in beta I backed up to the stable release. Hence my disappointment when it didn’t work as expected.
Actually, before reading about your tribulations, I had just assumed it would work without problem on the left nozzle after I tuned up the right nozzle. It was your report that made me wonder and wanting to check if there was a problem, as indeed there seems to be! So, thanks to you for the heads up. 
I could probably limp along with things as they are, but it doesn’t seem up to par.
I could tune a different “initial layer” flow factor for the left nozzle, but then it would be off for when it switched to the right nozzle, as both left and right nozzle share the same “initial layer” flow factor in the print process settings. Actually, that does seem like a fatal flaw all by itself in the slicer, because what if there were different materials in the A and B nozzles? It’s conceivable they might need different “initial layer” flow factors.
For that reason, an acceptable solution to me would be separate “initial layer” flow factors for the left and right nozzles in the slicer. Maybe Bambulab simply didn’t think far enough ahead yet to consider that possibility.