There is a problem. The trouble is that it doesn't affect
everyone. For instance, as soon as my subscription was accepted
into their system three weeks ago, it simply worked for me.
Unfortunately it's taking more time to resolve and I'm sure the
devs are tearing their hair out over this.
Sorry. I have no empathy with the developers hair. They chose to put the product on the market before it was in a satisfactory state. Now they say nothing other than perhaps it will work in the future (on other discussions).
One such other discussion suggests that the solution awaits a major update, for which the user would have to pay.
The real problem of course is that the server that they have contracted with iCloud is simply not powerful enough for the workload it is being asked to do. No amount of code is going to fix that.