Hummm, I'm 'bout out of ideas (that didn't take long, did it?)
Since the lenses are physically focused using the lead screw we think we know the camera is ok and the lenses can physically focus - since both lenses focus using LV it appears that Contrast AF works as it should - since one lens focuses when using Phase Detect AF (not LV) it appears that that function works and is configured correctly. So, nothing is broken??
If you can, I'd suggest taking your K30 and two lenses (one that focuses and the Tamron) to a camera store and see if they'll let you "test" the different combos. Or, perhaps you know someone who has a Pentax DSLR??
NOW I'm out of ideas....................