Every yuri anime flops anyway, not just Flip Flappers. It's sad.
The problem is that Flip Flappers was still great before it went full on yuri and it still did bad in ratings. It's just sad that niche series end up losing money so studios have to pump out recycled shounen/harem/ecchi garbage to stay afloat.
Well it did well enough to make money if thats what your wondering. But yuri has done well in the past for example kill la kill(a bit out there i admit) but its got yuri in it not alot but its there, yuru yuri is well there are people who dont like yuri demanding season 4... And flip flappers actualy turned a proffit as far as i know. Now we got ntr trap and citrus on the horizon and i expect citrus atleast to do well probly. Theres yuri in reni bokum (probly spelled that wrong but dont care) while more of a joke its not hidden away its embraced as just a thing that happens.