The issue of an intermittent problem with the address data is news to me.
The recent problem, now fixed ( in theory) was not an intermittency, but a hard disconnect, so to speak.
Adding to the confusion is the fact that QRZ summarily pulls data 1) at the request of the ham in question, and 2) worse (IMNSHO) apparently if a ham irritates QRZ enough.
Our use of the lookup at QRZ is worthwhile in that it not only supplies some personalized stuff from the ham’s QRZ profile, but tons of foreign info.
If you want FCC data, you can go to them directly of course.