Haven't seen that before... Does the Export UI refresh correctly if you adjust the size of Premiere's application window? What about when you switch back to Edit mode and then back the Export, does it refresh then? Also curious what happens when you close & reopen the project.
Nothing worked, not even deleting the user profile file from the folder so I had to delete everything relate to premiere pro beta and reinstall it again. It got fixed by itself but I still wonder what was the case. I could use TAB key to switch between options in the squeezed window but wasn't able to resize it.