Could you investigate why MPC-HC x64 always starts from the beginning of the video, and not from the selected frame?
When in Pictures Thumbnail Viewer I right-click and I select a frame, BSPlayer and VLC, both on my PC, don't have this problem: they start from that frame.
Is it something related to Media Player Classic x64 (the 32 bit version starts regularly at the min:sec selected) or something related to the parameters passed to MPC-HC x64 by Pictures Thumbnail Viewer?