Do you have the AdBlock extension installed. If so, try disabling it, and then quit and reopen Safari.
Go to Safari Preferences/Extensions and turn all extensions off. Test. If okay, turn the extensions on one by one until you figure out what extension is causing the problem.
Try setting up another admin user account to see if the same problem continues. Please post back on whether or not this worked. Also try the Safe Mode. Please post back on whether or not this worked.
Isolating an issue by using another user account
Safe Mode - About
Safe Mode Startup – El Capitan. also Sierra
If it works in the Safe Mode, try running this program when booted normally and then copy and paste the output in a reply. The program was created by Etresoft, a frequent contributor. Please use copy and paste as screen shots can be hard to read. Click “Share Report” button in the toolbar, select “Copy to Clipboard” and then paste into a reply. This will show what is running on your computer. No personal information is shown.
Etrecheck – System Information