I was playing as China, and holding at the yellow river, when suddenly I surrendered and Japan puppeted me as if they had won the war, but they had only occupied Beijing. I checked, there wasn't any naval invasions. I had 70% stability and high war support. I was at war with Gaunxi, who were in the Japanese faction, but they had already surrendered. It seemed like I surrendered when Shanxi (independant of me and my faction) surrendered, but I'm not certain.
This also happened when I was playing CPC and in the Comitern, and when I called the Soviets in, I insta capitulated.
This also happened when I was playing CPC and in the Comitern, and when I called the Soviets in, I insta capitulated.