Please see attached UE4_anim_interp_bug.fbx for a second example.
This works as expected in 4.7 and 4.8
I've got a couple different users reporting this now. I suspected animation compression to start with, but that may not be it because it only happens when you import into the Affected Engine Versions. If I upgrade a project with the assets from an Unaffected Engine Version, the animation looks fine.
The older engine version imported a timeline that went to 6 keys for the 5 key animation, the affected versions appear to truncate it to 5 keys in engine. I believe this was intentional for consistency with Maya/Max timelines. Either way, this odd behavior seems to be an unexpected consequence.
https://answers.unrealengine.com/questions/399599/import-animation-precision-is-too-poor.html
https://answers.unrealengine.com/questions/395317/ue4-animation-interpolation-method-works-in-a-wron.html
1. Import each of the attached fbx files (include animation)
2. Each animation should move the red cylinder into each of the green rings
3. Open the ue4_ani_precision animation
4. Scrub through the timeline
Result: Seems to hit only 3 locations between the beginning and end, none of which land in one of the green rings
Expected: Each frame places the red cylinder inside a green ring
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-29112 in the post.