precision 4.7==4.8==4.9==4.10==4.11[link text]
I was able to reproduce this and have entered UE-29112 in our system. These precision issues only seem to occur on very short animations like this. It appears to be truncating a key from the end.
There is a workaround though. Import your animations to 4.8 (where it works), then migrate those files to a later engine version.