using 5.3 here sometime when i save animation montage it crashed and it breaks the character

the character mesh disappears character movement is not working i can’t find the way to fix it

i though it is my custom character and character movement component classs in c++

but after i reparent it to default one it won’t fix it… this error is very critical because once it happens

i need to roll back the project again

so i use the back up project instead everytime anyone knows how to deal with this?