The page didn't get converted properly [HTML2WP]
Make sure you have uploaded all the files properly - including .css and javascript.
If the issue persisits, please open a support ticket and attach a zip folder that has in it one html page, as well as the images, .css and javascript for that specific html page.
Leave out any unnecessary big files like videos.
The zip folder should be up to 1 megabyte in size (preferably much smaller).