I have the same issue. It used to de-register the previous computer automatically, now it just tells me that it can't do it.
Why make your user's life so hard? You moved from an automatic process to one the forces your users to contact you and for you to do manual work.
It does not make any sense
I no longer have access to the other machine. I am paying a yearly subscription. Please make it easier for individuals to use your product. The automatic process made sure that we cannot use the software on more than one machine anyway. Why remove it?