What's mildly irritating you today?

[xoxoxoBruce]

Either the torque wrench is calibrated wrong or I'm using it wrong. But it worked perfectly on the first bolt.

Nope, can't make that assumption.
Some bolts, as designated by the manufacturer of the car, are not to be reused, the service manual should tell you which.
That bolt could have been over-torqued by the factory on anywhere along the way, causing it to be sub standard.
The bolt has been around a long time, nobody know the trouble it's see.
A burr or foreign material can cause binding which would require more force to overcome than the bolt is rated for.
Most nuts and bolts are oily enough to prevent galling, even though they look shiny clean. It can gall in a fraction of a revolution, and when it does you're generally screwed, not being able to move the bolt in either directing without breaking it.

Did you get the snapped bolt out?