A Child PlayerCharacter BP in this project resets its assigned Anim BP to 'None' on restarting the project

A Child PlayerCharacter BP in this project resets its assigned Anim BP to 'None' on restarting the project. The user reports that the Skeletal Mesh will also occasionally reset to None. I have not been able to reproduce this in a new project.

This is the link to download the user's project:
[Link Removed]

The BP that does this is BP_PlayerCharacter_Engineer, which is a child of BP_PlayerCharacter. This does not occur with the parent.

Reproduced in 4.8.2 and Main (//depot/UE4/Promotable-CL-2623091)

1. Open the user's project (download link in Description)
2. Open the BP_PlayerCharacter_Engineer Blueprint
3. Select the Mesh component
4. In the Details panel, switch the Anim Blueprint Generated Class to ABP_Player
5. Save All > Close the editor > Reopen the project
6. Open the BP_PlayerCharacter_Engineer BP again

Result:
The Anim Blueprint Generated Class will be set to 'None'. The user claims the Skeletal Mesh may also be set to None, but I have not been able to reproduce this.