My old Whatsup 0.1.9 on Jolla 1.1.7.24 works like usual. Also updated to the new 0.1.9 test release. Also working like a charm. German Number +49.

I don't really know the WA Protocol good enough, but my strategy for not get banned is simple:
- Dont register the same number on different devices / clients
- Dont change Sim-Card on the Jolla, which is alredy registered and working
Thats all. I was never banned. After Mitakuuluu 2.x has stopped working i got to the Android WA, and now i'm on WhatsUp since the first public beta from Cepi. (Thanks Cepi for your Work, btw. alredy donated twice).
This is also the reason, why i don't use Mitakuuluu 3.x.
Next week i get my new Jolla, because my old (The first one) has a yellow burn-in on the display and the battery is almost on the EOL. I will try to register my number on the new Jolla over WhatsUp again, on the old one i can than try Mitakuuluu 3.x