I tried to import SCORM courses into Moodle. Lot of these courses could be imported, but several ones couldn't be imported. No error message, just a blank screen. After some debugging (I set $db->debug=true and I turned on the error reporting) I found that the error was occured because the 5 seconds timeout exceeded. In php.ini the timeout value was 30 seconds. I continued the debugging and found the timeout setting statement in the "moodle\mod\scorm\locallib.php" file in the scorm_delete_files($directory) function. The course was successfully imported after I removed the statement.

I think, this statement causes the error, because it overriddes the the default php.ini value. It restarts the max_execution_time counter, but only 5 seconds remain to finish any other operation after last set_time_limit() call. If the course is "big" this time value isn't sufficient.