Noise Options not working in PNoise Analysis

I am trying to use the noise options from Options->Analog to turn off the noise contributors in a buffer that drives a clock to my test circuit. I am measuring the jitter of the clock at the output of the test circuit so I am running pnoise jitter analysis.

When I leave the noise options untouched I measure an expected amount of noise and am able to break it down and plot the noise on a per instance basis with Direct Plot->Main Form. The input buffer is just to create realistic edge rates and I do not want to include its contribution to the jitter measurement. So I go to Options->Analog and under Noise Options set Noise Contribution to "off" and then for Instance List I select the instances I do not want to include (input buffer). Everything runs fine. I expect a minor reduction in jitter by excluding the buffer (I know from the untouched noise options sim who my biggest contributors are). However, the result shows a tiny amount of jitter. Through investigation I find out that all of the transistors are contributing no noise, even those in my test circuit that are not specified in the noiseoff_inst list. There are only a couple of resistors in my test circuit that have noise. I try the opposite approach and tell Noise Options to only include noise from my test circuit --- this leads to zero jitter! I have tried both ADE and ADE XL as well as pnoise jitter and pnoise timeaveraged -- the behavior is the same for all.

I did a quick check with transient noise analysis using the same options. I can see the jitter after input buffer nearly disappear when I use the same method to turn off the noise of that buffer -- the noise options appear to be working for transient. I understand from documentation that these options should also work for pnoise.

I am using ICADV12.2-64b and MMSIM Version 15.1.0.284.isr1.

Thanks,
- Phill