Built a workbook to track audit prep tasks for my internship and now it's gotten out of hand in a way I don't fully understand anymore

I started simple. One sheet, a list of tasks, a status column with a dropdown, a due date column, conditional formatting to turn rows red when something was overdue. That was fine and I used it every day and it was genuinely helpful. Then I started adding things. I added a summary tab that pulls counts by status using COUNTIF which works fine. Then I added a column for "assigned senior" because I wanted to filter by person, and then I wanted the summary tab to break down by senior too, so I wrote a COUNTIFS with two criteria and that also works. The problem is I then tried to add a column that flags tasks where the due date is within 3 days AND the status is not "complete," and I wrote something that I thought made sense but it keeps returning TRUE on rows where the status actually is complete and I cannot figure out why.

The formula I have in the flag column is =AND(D2-TODAY()<=3, C2<>"Complete") where D is due date and C is status. It looks right to me when I read it out loud but two rows that are marked Complete in column C are still flagging as TRUE and I've checked the spelling three times. I'm wondering if there's a hidden space issue in the dropdown values because I set up the validation list by typing directly into the data validation box and not referencing a range, but I'm not sure how to check that efficently without going cell by cell. The broader question is also whether this whole structure is getting unwieldy and I should just use a proper table with structured references instead of normal ranges, because right now any time I add a row I have to manually drag formulas down and it's starting to feel like I'm fighting the file more than using it.