When moving frames around on the Timeline, changes don't show up in the playback until hiding/unhiding the layer.
it happens when cache is rendered,and doesnt register the changes in the frames,i think.
not ALL cache needs to be dumped,only where the changes occured.
I think I have fixed that bug yesterday. The timeline and cache rendering got blocked after every save or autosave operation.
Please reopen the bug if you face this bug in any nightly build after 29/03/2018.
*** This bug has been marked as a duplicate of bug 392233 ***