We have noticed that many carriers only support tethering through their own APN.
This means that if you install the Snappli APN then the tethering option will become unavailable.

The current workaround is when tethering is required the user uninstalls the Snappli APN.
Once tethering is complete then open the Snappli App and tap Info | Carrier to reselect the APN to install again.
All data will be saved as long as the app is still installed.