When I drop dimension of home office (HO) the % for deductions increase (33% to 50%) - doesn't seem correct. How do I ensure the correct % is calculated?

When you enter your home office deduction you will see this screen that will tell you what percentage of your overhead expenses will be allocated to your home office:

Also, when you print your tax return, you can look on form 8829, part one where your allocation of square footage will be listed.