So I'm certain I'm not the first to post this but there's a problem with the approval system related to populations with ideologies "not represented in the Senate". For example you play Cravers and have 5 military, 2 ecology (caused by civilian fleets), 3 science (caused by....science). Said planet has an approval rating of zero, happens to be your capital, and rebels less then 20 turns in. Why's the approval rating at zero? Because approval for populations with representation in senate, meaning the 5 military, only generate 6 approval. That's alright I'd even say that's a balanced amount. However the populations without representation......generate -60 approval. That's literally 10 times what the number should actually be. At least I hope this is a bug. Otherwise factions with a dictatorship are literally broken as there is no way to prevent an absolute anarchy. Hell even Horatio, who have an enormous amount of bonus approval possibilities, can only go on for so long before their entire empire implodes. And this doesn't get easier to manage as the game goes on the bigger you are the easier it is to fall as every population who isn't religious(Horatio) or isn't militant(Cravers) will literally capsize your efforts by generating way too much unrest. And if you start with something other then a dictatorship but have an empire rebellion anyway you default to dictatorship and then you are completely doomed. 

I'm currently stuck in an endless spiral of Dictatorship with either the Ecologist or Industrialist faction as the only faction that is represented, then Anarchy because everyone else is unhappy about not being represented, a brief respite as people are happy about Anarchy, then another Dictatorship....

I don't understand why the change from Dictatorship-> Anarchy -> Dictatorship is considered a change in government, but every time it's set to Dictatorship the timer for how long this type of government is locked in is reset again. So I'm perpetually 60+ turns or so away from being able to go back to a different government type with more than 1 political party, but every 3-5 turns my people rebel and I get switched back to Dictatorship. I neither have the manpower nor the luxury resources to bribe everyone and even the systems with my heroes (which bring an approval bonus) are rebelling. By now I just keep strong ships in the systems where it's the worst and kill any insurgents....

At least I can see that all the other empires are losing planets to rebels as well. 

But yeah, this is really tough and I'm only playing on normal difficulty. *shrugs*

Yeah, there's a number of threads on page 1 on this.  

This one is the most informative including a temp workaround: 

https://www.games2gether.com/endless-space-2/forum/65-general/thread/23394-huge-decimal-point-bug-approval-in-new-patch