Hey there,
I had this problem for a good time that drove me almost crazy.
But I did find a solution I thought I would share.
1) Completely uninstall quicktime
2) Open after effects, go through error messages and try to import your clip, which of course wont work, but carry on.
3) Close after effects
4) Install latest quicktime again
5) And there you go, i couldn’t believe it when it worked for me, but hey.