"Amount Includes Tax" check box on the Details page for an Expense Claim - visible to some users; no

I apologize for this question being posted in the Payables community. There was no selection under Oracle E-Business Suite for 'OIE' or 'Internet Expenses' or 'IExpenses'.

I am looking for assistance in understanding why some of our OIE (IExpenses) users can SEE a check box labeled "Amount Includes tax" when creating expense claims, while other users cannot. I have verified the profile setting OIE:Tax Enabled and it is set at the SITE LEVEL to 'Yes'. Individual users do not have a value set for this profile and yet there are some users that cannot see this check box when creating expense claims for expense types where the "tax is included".