I have same problem when editing thumbnail or trying to do bulk actions ( copy, move, delete etc)- the dark overlay won’t let select /click anything, whole window need to be closed to unfroze the window. Latest wordpress update did not fixed this neither….
very disappointing, still the only way is stay in version 1.9.13 because new ones were non usable….
Does anyone know if it helps the above problem if to go back to more older version?