We had this exact same issue in 4.27.2 and unfortunately believe it is a bug in the engine, we have been able to fix it by patching the engine as follows:
At line 64 in the github link below, if(!InputOboeStream)
should be changed to if(InputOboeStream)
(exclamation point is gone).
To patch the engine, we followed the following guide Building Unreal Engine from Source | Unreal Engine Documentation .