I have the same issue. I posted a message yesterday in the current EP event thread. It seems that the developer bases were turned off when this current weeks event started, as I stopped getting the level 10 developer bases and started getting loads of tiny bases to attack. What you are most likely seeing now is that because there is a conflict on Hoth and lots of people are attacking we have gotten to a point where all these mini bases are now under protection, hence when you try and attack you get CNFO message. I had to use squad perks and crystals to get off Hoth yesterday, and while I continue to see these mini bases on other planets I think I will be avoiding Hoth just in case.
What would probably help is for everyone who experiences CNFO to log a support ticket with Disney. The more people that do that complaining about CNFO then the more likely they will be to switch back on the developer bases.
Main Account: Bacon (level 10). LINE ID: sgu97cab
Second account: nEggs (level 8)
Squad - NewSithEmpire