Since the error is:
ERROR: Brick datablock "brick1x2x2Data" has the same uiname as "plate1x2x2Data" (1x2x2) - removing.
BackTrace: ->ServerSettingsGui::clickLaunchGame->createServer->onServerCreated->verifyBrickUINames
There is a brick that has the same uiname (1x2x2) and it is a plate (plate1x2x2Data)
I looked through my Plates section on the brick GUI, and found this:

Could this be it?