Overallocation is not that simple. You could have a person who works an 8
hour day and has a maximum allocation of 100% assign to two 1 hour tasks on
a day and still they show overallocated. How can that be? 2 hours = 25% of
8 hours! The answer is both tasks are occurring at the same time, say 8 to
9 in the morning. Even though the total hours for the day are fine, they
still can't be two places at once. Change your date format to one that
shows both date and time and examine the tasks this person is working - I'll
bet you'll find they overlap. Level on an hour-by-hour time frame and it
should fix it.