Do you have the same issue if you follow the OP’s steps to reproduce it?
Provide extra information to complete the original description of the issue:
Even when cold and dark the fuel will crossfeed from the right tank to the left. Trying to enable the crossfeed after startup has no effect. Plane remains imbalanced and impossible to fly properly. Restarting flight has no effect imbalance persists.
If relevant, provide additional screenshots/video: