unable to enable in-app purchases (In-app purchases button is inactive)

Hi, I am unable to enable in-app purchases. Checked under Restrictions, but the In-app purchases button is greyed off, it is inactive, and nothing happens when trying to press it. I am able to purchase and download apps, payment details are ok. I have been able to make in-app purchases before. My apple ID is the same. Im am able to make in-app purchases on my Ipad, same apple ID.

The only things that come to my mind are that the situation on my phone changed, I think, possibly, when my credit card got stolen and I obviously then changed payment details to another credit card. OR, it happened when I returned to work and my company was given Device Management rights. Could either of these have somehow restricted the use of in-app purchases, so that I am unable to make this choice on the phone? How do I change it? I really need some in-app purchases to upgrade certain apps.

Please help!