[Bugfix] Fix showing categories when editing thread (#3899)
[Bugfix] Fix showing categories when editing thread (#3899)


Submitty/Submitty,RCOS-Grading-Server/HWserver,Submitty/Submitty,RCOS-Grading-Server/HWserver,RCOS-Grading-Server/HWserver,RCOS-Grading-Server/HWserver,RCOS-Grading-Server/HWserver,Submitty/Submitty,Submitty/Submitty,RCOS-Grading-Server/HWserver,Submitty/Submitty,RCOS-Grading-Server/HWserver,Submitty/Submitty,RCOS-Grading-Server/HWserver,Submitty/Submitty,RCOS-Grading-Server/HWserver,Submitty/Submitty,Submitty/Submitty