The Editor freezes during PIE when loading a .sav file from 4.7 in a 4.8 or 4.9 project

The Editor freezes during PIE when loading a .sav file from 4.7 in a 4.8 or 4.9 project. The user reporting this reports a memory leak and crash, but I have not been able to reproduce that in particular.

Test project from 4.7.6 with an already saved .sav file:
[Link Removed]

Note that the PlayerController attempts to Load Game from Slot on Begin Play. If the .sav file from 4.7.6 is removed from the file directory (or all Load functions are disabled), PIE does not freeze.

Reproduced in 4.8.1 and Main (//depot/UE4/Promotable-CL-2598545)

1. Download the test project from [Link Removed]
2. In Windows Explorer, create a copy of the project folder
3. In the copy, switch the engine version to 4.8 or Main
4. Open the project copy
5. Make sure the MyLevel map is loaded
6. PIE

Result:
The editor will freeze and remain frozen indefinitely.

Memory Leak in 4.8 from migrated maps when play in editor