Editor crashed when selected the property menu of the copy of a track with animation blend.

Alternate repro:

1. Create a new level sequence
2. Add a skeletal mesh to the level sequence
3. Add an animation track and animation section
4. Add another animation section and blend the two together
5. Copy the skeletal mesh in sequencer and paste it (there should be the same tracks pasted)
6. Save the sequence
7. Right click on the level sequence in the content browser, Asset Assets->Reload
8. Open the sequence

EXPECTED: Both animation tracks on the two skeletal meshes should look the same (both have blends)

Original repro:

1. Create a level sequence and add a bp with a skeletalmesh component.
2. Add two animation sequences and blend them on the bp's animation track.
3. Copy the bp track, save the sequence and clos the UE editor.
4. Reopen the editor and found the copied track of the bp in the sequencer lost the blend part of the two animations.
5. Right click the blend part and selected the property menu, the editor would crash.
6. The bug reproduction projection is attached here.[Link Removed][Link Removed]