I have the same issue.
What is your GPU ?
Same problem here...
You have a bad monitor profile. Lightroom is particularly picky about the monitor profile, and will let you know if it's not happy with it. A profile that Photoshop finds perfectly allright can cause problems with Lightroom.
The solution is to calibrate your monitor with a hardware calibrator.
As a diagnostic tool and a temporary fix, try setting the monitor profile to sRGB. See How do I change my monitor profile to check whether it’s corrupted?
Sometimes Lr can not create library module previews after immediately the adjustments applied in the develop module ... so creating previews manually with the related menu item can help ... or you can enforce Lr to create library module previews by opening the loupe view in library module and 1:1 view.
But the exporting JPEGs should show the adjustments made in the develop module ... it is strange.