Happy New Year

First of all, capitalizing each word makes your post very hard to read. Please use normal capitalization and punctuation.

Second, your subject heading says Massachusetts but you posted in the Montana forum. Which state is it?

You're still capitalizing each word.

Cut it out. I mean it.

It is legal to require you to use sick time (or vacation time, or personal time, or any other kind of paid leave time) when you leave early. However, if you are out of paid leave, you still have to be paid for the entire day UNLESS the illness is one that would trigger FMLA. You do not have to be paid for any time attributed to FMLA regardless of whether it is in full day or partial day increments.

It is by no means unusual for payroll software to default to 40 hours regardless of the number of hours worked. It's not saying that you're only getting paid for 40 hours - it's simply a software thing.

I have no idea, based on what you have posted, whether you should be getting OT or not. You have not posted anywhere near enough information about your job duties to say.