after i import my character and animation the weight painted meshes and bones gets messy why?!

so I’m making this horror game and i designed my first character, rigged it using blender and finally animated a walking cycle in it. ===> Screen capture - 058d042a81e474dde33af951188eb456 - Gyazo

now when I import both my animation and not animated model separately into .fbx(s) the only attached objects in the animation fbx are the ones that are completely attached to a bone [not using weight maps just using ctrl p and bone in blender]==> Screenshot - 53e56430edc353c27725c3f9c550719d - Gyazo

the model itself which has no animations on it looks just fine after importing ==>Screenshot - 285326d5b5310457d2f65484179a0e0e - Gyazo

please, any tips:p? I’m just a beginner