If an actor has 'Simulate physics' enabled and the Collision Enabled field is set to anything other than Collision Enabled (i.e. OverlapAll sets this to No Physics Collision) then mass is reset to 1.0.
1. Download the attached project
2. Unzip it and right click the .uproject file and select 'Generate Visual Studio Project Files'
3. Open the visual studio solution file (.sln)
4. Compile the project (ctrl+shift+b)
5. Open the .uproject file
6. Notice that the New Blueprint's Collision Enabled field is set to No Physics Collision
7. Start PIE
8. Notice the debug outputs at the top left. Both objects' mass should be output as 200.0, but one is shown as 1.0.
Head over to the existingAnswerHub thread and let us know what's up.