Hi,
i try a lot of VPN Providers in the last week. PureVPN i didnt chek, but in sum i can tell you this:
It seems that it is not necessary to have a real dedicated ip, but for sure you cant use a Provider where the ip adress changes really dynamic. so like there are providers where the connection to the server changes every few minutes cause of the best server.
Nord VPN worked best, perfect privacy and some others also worked, but it depended on the server (without dedicated ip) and in the last days from a few customer i heard the same as you say, it worked with their provider for a long time and then suddenly it didnt worked. the customers just tested different server locations and then it worked again.
for sure when you have a dedicated ip, thats not so nice, but often even if you have a dedicated ip you can choose also the normal offer server from the provider so i would say, just test the other servers without dedicated ip