I too have received this email for a couple of classes that I signed up for, but I have yet to see any other information than this, so the title seems a little premature, at least in phrasing it this tersely, which implies that there is some kind of insurmountable problem, but really there is just no more information.
Apparently "all" is an exaggeration, but I have received similar emails from the two courses I signed up for. The telltale paragraph seems to be "Unfortunately, there are still a few administrative i's to dot and t's to cross." So the problem isn't technical, it's likely political.
They cite administrative reasons in the email but no professor or teaching staff has said anything in the open.
The twitter accounts of the classes did not say anything clear regarding the reasons.