Unable to use Steam Sessions with a source built editor from Github

Steam sessions are unable to be found in packaged games that use a source built editor from Github. According to users, this is related to the BuildId not being set properly so the packaged games are not able to see each other. This also may be related to the CompatibleChangelist and Changelist field being empty, but that was also the case in 4.19's release.

This can currently be worked around by adding a BuildId override to the following lines to the user's project's defaultengine.ini in the OnlineSubsystem section:

bUseBuildIdOverride=true
BuildIdOverride=[AnyNumberHere]

Regression?: Yes
This did not occur in 4.19.2

Note: This has not yet been tested in Main. That is currently being tested.

1. Download the attached project
2. Download and build a source built editor from Github
3. Open the project in that new version of the editor
4. Package the game for Win64 Development
5. Place the packaged game on two machines that are both signed into Steam with separate accounts
6. On computer A, open the project and press Create
7. On computer B, open the project and press Find
   Result: Computer B fails to find Computer A's session
   Expected: Computer B joins Computer A's session