As I understand this plugin is no longer maintained (see this: https://devfarm.it/forums/topic/almost-end-of-support/ )
It looks like it uses so called ‘legacy’ interface to NGG… NGG removed some bits of it with release 2.0.71 and then reintroduce them back in release 2.0.76.1, however this did not fix the problem. I’ve asked NGG to help us. They promised to look at it, but priority is low and no sla is given. I checked the code and believe that the ‘bug’ might be in NGG (I could be wrong here… it is just a ‘feeling’).
The problem could also be fixed if someone change plugin’s interface to NGG from legacy api to the new one. I really don’t have time for it now and seriously doubt I would have it soon. I also don’t have ‘test/dev’ environment(s) to play with it.
It would be VERY beneficial to everyone if someone would come forward.
Regards