After creating a massive managed navigation menu system via the managed metadata term set for a team site, I found that the sub-sites were no longer inheriting the Global Navigation menu. After some research and coming across a post containing some C# code that applied the fix and hinted that it could easily be converted to PowerShell code, I determined that the inheritance only needed to be reset and there was no need for code.
With the quick flick of the Global Navigation radio buttons, this issue was quickly resolved, here’s how:
Click ‘Settings’ > ‘Site Settings’ > ‘Navigation’
Select ‘Structural Navigation’
Click ‘Navigation’ again and select ‘Display the same navigation items as the parent’ and click ‘OK’ once more.
Your managed navigation menu from the parent site should now be displayed on the child site all with out a single line of code.