Odd blue box in cell with a formula

Hello all.

I'm making a payroll sheet and I have two columns at the end for each employee where I use a formula to add up the hours for both regular and overtime.

However, as you can see in the attached picture, the very first cell with the formula displays this blue box/gradient that takes up half of the cell. It doesn't seem to do anything or alert me to some error I made and it doesn't happen with any other cell except for this one. Right-clicking gave me no information about it, either.

I wouldn't mind so much, except that it also appears during a print preview and I'd rather not have this little oddity being there when I need to print this out. Does anyone know what this is and how to get rid of it?

Much appreciated.