Animation on certain bones messed up after fbx import

Animation created and exported from Blender as .fbx. After importing into UE, it shows odd bone rotations.
It happens both at keyed frames and non-keyframes. It rotates few times in 120frames while the animation curve is flat.
It does not happen when I import it in other platforms (ie Unity).

It should be a fist, but bone on index finger rotates (about 180deg) now it is pointing out.

Graph editor in blender shows the curve is flat after keyframe at frame 12, the glitch happens on ring finger beginning at frame11 and on index finger at frame50, it does not show correlations between the curves and the glitch. )All fingers have similar curves)

Export settings in Blender.

Import settings in UE

This happens on UE 4.26, but problem carried over to UE5 early access as well.

Any help appreciated, thanks!

I have this problem too.

I do have a similar problem. For me I imported from iClone7. hope some one can assist