My refund amount doesn't change despite adding or deleting a bunch of deductions. Is there something wrong with the program? I've never encountered this issue before.

It depends on what deductions and credits you're adding and deleting. If you're playing around with non-refundable credits, they're not having an impact on your refund amount because non-refundable credits can only reduce your tax payable (in other words, they don't increase your refund).