It appears that one something has been set to flex and contains a div but you then change the flex to display, the containing div still thinks it’s flex. so you can no longer set width or height depending on the previous flex option.
Can you make a video recording if this can be replicated? I was unable to make it behave so. Perhaps your actions are different?
I would try and post your feedback on the new style panel under this topic. The staff is monitoring that one closely 
A post was merged into an existing topic: New Style Panel Feedback