Fix for flicker seemingly caused by swapping display block/none

Closes #3492862

To test this, I've found that making a series of rapid updates to the props form on a page that has > 10 components on it and staring intently at the preview seems to show the issue before my fix and then doing the same after applying this MR seems to not flicker.

You can also record your screen and then step through frame by frame - you should not see a blank space where the preview should be on any frames.