Nips didn't have much reaction until the last 3 episodes where lots of complaints arose, and the director got lots of heat on Twitter from fans. The author had to write something to retcon it, and then the story came out.
They wanted to get to a point where they could adapt volumes 9/10 and 11/12 as respective seasons, but they had 3 to adapt before then. The author and producer were brainstorming ideas when the director ignored them completely and did his own thing with planning. When they asked him to stop, he told them to go fuck themselves and said that the series was only popular because of him (the adaptation). He thought that he could write better than the author, and then had the nerve to hand the completed anime original stuff to the author and had him script it to episodes. Needless to say the Japanese fans flipped their shit by the end of the season with many saying they weren't gonna buy it, and more saying they would only buy it to see the coming volumes animated.
And yes, the author damage controlled hardcore before the season and began airing. He basically said screw it and got Kadokawa involved, and they sided with him and completely cleaned house with the anime staff, firing everyone except the composer and seiyuus. Then they found a new studio to adapt it, and here we are.