Yes the PI 1944 does not get the research it deserves as been the actions that broke the back of the Japanese defence strategy of island chains protecting their commerce ships supplying the home islands.
George MK. I's defective telescoping landing gear. However, I believe that early models suffered from a defect where the hydraulics would fail mid flight and the landing gear would drop down.
There was said to be a problem with landing gear/doors opening by themselves in over >400kt dives. It may be in Genda's Blade book? Or J-wiki? Too many obscure information bits in my head without references