I have no concrete answers, but this was fairly common with the Sync for Reddit app as well. We'd go several months without updates before they'd resume for a while and then drop off again.
I'm relatively confident the same will happen here, so updates will probably return soon^TM .
It's definitely still chugging along, although I will point out that the sub numbers now include not only modern WoW players but also Classic players. If the 7 million number is accurate, that's 7 million across all WoW versions, not just modern WoW.