I have several 50 1.5's -one Opton and 2 Jena
Haven't run into the problem myself but have certainly read about it and I think Zeiss discontinued the modern versions for Canikon recently but I wont speculate on the reason.
I really like the lens and it enjoys probably 85%-90% preferential treatment on my II.
I have the Jupiter 12 and went through 3 to finally get a decent one of those but the jury is still out and I'll probably come up with anothe wide solution.
OP, do you have a wide for your Kit and care to comment…anyone?