Found the solution.
Coming from the Apache world, this is the first time using IIS (10). I edited the applicationHost.config file and removed the following handlers lines
<add name="TRACEVerbHandler" path="*" verb="TRACE" modules="ProtocolSupportModule" requireAccess="None" />
<add name="OPTIONSVerbHandler" path="*" verb="OPTIONS" modules="ProtocolSupportModule" requireAccess="None" />
and edited the PHP_via_FastCGI handler to
<add name="PHP_via_FastCGI" path="*.php" verb="*" modules="FastCgiModule" scriptProcessor="C:\Program Files\PHP\v7.2\php-cgi.exe" resourceType="Either" />
I then restarted IIS and all the routes started working. Hope this helps someone else.