Measured VS Ltspice Difference in P-Chan JFET Attenuator
What is the measurement resistance of your meter? If it is 1155kohms then that would explain the collector voltage of 12.6V. But, would that explain the gate voltage of 9.2V?

9.2V divided by 1155kohms is a current of 7.97uA. What current thru 220k+470k would drop 5.8V? Answer 8.41uA. Near, but not proven.

If only that current were flowing thru the gate, could we expect to see 12.6V on the collector? That current would drop 1.85V across the 220k. The OP has measured (by implication) a volt drop of 2.4V.

There are discrepancies here that might easily be explained by the meter the OP is using and this is my suspicion.

One simple test - disconnect the gate and re-measure using the same meter - is the voltage the same - try measuring the 15V rail thru a 220k - is it still 15V or somewhat less?