Yes. I am using fixed ISO. Not ISO auto. You definitely want fixed ISO.
Based on testing of my own and others (kozlok, Ole to name a couple) here's the behavior on metering with the K-50 and I'd guess the K-30. The below assumes you've set the aperture ring to enabled and M mode with theTvShift. And if using M42 lenses, or I would think many other older lenses, with the man/auto setting on the lens set to manual:
1.) Camera set in M mode:
A.) live view will meter with green button.
B.) Non live view will not meter with green button. The shutter speed is simply set to an approximate 1/ISO based on fixed ISO setting.
2.) Camera set in Tav, Av, Tv, or scn mode (each of which simply renders only Av mode, based on aperture ring enabled setting, as best I can tell):
A.) With either Live view or no live view the camera meters correctly via the green button. It'll even meter correctly if you extend the built in flash. It'll raise (make faster) the shutter speed accordingly.
3.) Camera set in U1 or U2 mode selected it gets even better
. Still the camera is in Av mode but now you're a bit closer to fully automatic. i.e:
A.) If the ISO was fixed it will move to ISO auto and you can meter (green button) with or without live view. So in this mode both the ISO and shutter speed change based on the metering. And extending or not extending the built in flash unit will also affect the shutter speed/ISO. with or without live view.
So User modes 1 or 2 would be the way to go unless you're looking to have more manual control over the shutter speed/EV, etc.
So I humbly retract my earlier complaints. I think I see a method to the engineers madness.
Try it and let me know if you find the above to be true.