Can try it :
- in Settings/Access Point, you have a profile of your network, call it is (1)
- now, creat a new profile with same settings in (1) --> call it is (2)
- touch & hold (2) and select "activate", wait a moment when (2) is actived.
- then, active (1) again
- reboot your phone
- cellular --> on, internet sharing -> on, internet sharing will work