header image height display Improperly.

Brother john report

Header suddenly unable to display anything over 198px high. Header created 900px x 300px previously displayed fine.

Since the cause of this problem is not known yet however, it is clear that it must get over, we announce you a provisional solution.

I want me for the person who faced the same problem to teach as much as possible to what kind of timing it becomes so.

quick fix code below

add to functions.php