Drag file to timeline and Undo stack disappears in VP15 Build 361.

Repro:

1. Start VP15

2. View -> Audio Mixing

3. File->Import: Select a WAV file.

4. From Project Media Pane, drag the WAV file to timeline.

5. Make some changes on the timeline (e.g. display volume envelope, add some points, shape volume)

6. Drag the same WAV file again from Project Media Pane but to another track. Now have two tracks with audio.

7. Try to undo, via Ctrl-z or look for Undo under Edit.

The stack of changes made at Step 5 is gone.  Can't undo.  All that appears under Edit is "Undo Track Name Change." Clicking that does nothing.

Sorry if I'm missing something, but every once in a while I do this and I hate to lose all my previous commands.

Lenovo Y900 (SKYBAY U3E1 Motherboard), 32GB RAM, NVDIA GTX 980, Windows 10 Pro Build 16299.492