Hi!
This extra space exist in all OPS/OJS/OMP3.2+ fresh installation and hence its not upgrade or plugin specific issue. This empty space automatically disappear when you have submission list (space by list greater than the screen itself). In the case submission list is not enough the page can be scrolled down and this empty space exist. I am sharing 2 screenshot which may explain in a better way- (Extra space appears after scrolling down if the screen is empty due to less submission list)
