Try the following:
Open Mobile hotspot settings (Settings > Network & Internet > Mobile hotspot)
Turn on mobile hotspot
Under "Related Settings", click Change adapter options
Take note of which adapter is connected to the internet and which adapter is your mobile hotspot (typically named "Local Area Connection\* [#]")
Right click the adapter that is connected to the internet and click Properties
Go to the Sharing tab
Uncheck "Allow other network users to connect through this computer's Internet connection". If it is already unchecked, skip this step.
Click OK
Again, open Properties > Sharing for the same adapter.
Check "Allow other network users to connect through this computer's Internet connection"
(If you get a popup that says "Internet Connection Sharing is currently enabled...", click OK.)
Under "Home networking connection:", select the mobile hotspot adapter
Click OK
Problem persists:
Open Start then type: regedit
Right click Regedit then click Run as administrator
Navigate to the following registry key:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\WlanSvc\Parameters\HostedNetworkSettings\
Delete the following key:
HostedNetworkSettings
Restart then try again.
Run the Network adapter troubleshooter
Open Start > Settings > Update & security > Troubleshoot
Scroll down, select Network adapters
Click Run the troubleshooter
When complete, restart to see if it works.
If not, you can try updating both your Network adapter drivers or uninstall them.
Press Windows key + X
Click Device Manager
Expand network adapters
Right click your adapter, click uninstall
Exit Device Manager then restart
Windows 10 will re-detect them and reinstall them.
Try setting up mobile hotspot again.