Blueprint derived from C++ class not saving correctly

The blueprint that the user is using loses some data when the editor closes and reopens despite saving all of the content.

Note: Currently unsure of what exactly causes this but as I am able to reproduce the issue, I'm putting in a bug report.

1. Download the test project: [Link Removed]
2. Unzip the project, right click the .uproject file and select 'Generate Project Files'
3. After the project files have been generated, open the .sln.
4. Once the .sln has loaded, hit ctrl+shift+b to compile the project
5. Once that has finished, double click the .uproject file to open it. (If you receive a message asking you to download the substance plugin, hit 'No' and the project will open anyway)
6. Once the project has loaded, hit 'Play' and hover over the hex map with your cursor (you may need to turn the camera to see it)
7. While hovering over, hit H over different hex tiles.
Result: The output that is printed says 0, 0, 0, and also says in the Output log that 'None' is being accessed

The Expected result will come from these steps, as it works around the bug:
1. Hit 'Stop' to stop the simulation.
2. Select 'HexGridManager1' from the World Outliner
3. In the details panel, expand the 'Grid Size' field and change either the X or the Y to a different value than the current values
4. Repeat steps 6 and 7 from the previous set