All forms of Tethering work for me (on T-Mobile in the US), but with a rather large catch: only sites that use SSL (HTTPS). If I want to take a look at non-secure sites, like XDA, I have to connect to my home VPN. No VPN, no HTTP, only HTTPS. It's very odd, but the the behavior makes me think T-Mobile is probably blocking it. It will send the HTTP request out, resolve the host, but then stall on "waiting for [name of site]." I don't get a redirect page or anything, just nothing non-secure when I'm not on the VPN. I'm on T-Mobile's $30/month 100 minutes, unlimited text and data plan.
There's also a chance it might be related to the Android 4.4.2 tethering bug, as when I'm connected to the VPN, it doesn't rely on Android to process HTTP requests.