Preset appears applied, but Saturation and Color Mixer settings remain unchanged on some photos

Description of issue
I use a Develop preset that lowers the global Saturation slider and changes color values in the Color Mixer. On some photos, every preset adjustment is applied. On other photos, the preset appears to have been applied, but the global Saturation and the intended Color Mixer values do not change at all. This is easy to miss because the preset still looks applied. I have observed this on two different Macs running up-to-date Lightroom Classic. I am reporting my own observations, not claiming that every user or photo is affected.

Steps to reproduce
1. In Lightroom Classic, use a Develop preset that includes a reduction in global Saturation and changes to Color Mixer values.
2. In the Import dialog, select that preset under Apply During Import and import a group of photos.
3. After import, inspect the global Saturation slider and Color Mixer values for individual photos, including photos where the preset appears to be applied.
4. Select an affected photo in Develop and apply the same preset again. Check those values again.

Expected result
For each photo, the preset should set global Saturation and the included Color Mixer values to the values saved in the preset, whether applied during Import or reapplied in Develop.

Actual result
Some photos receive all the preset changes. On other photos, the preset appears applied, yet global Saturation and the included Color Mixer values remain unchanged. Reapplying the preset does not correct those photos. The behavior has occurred on two different Macs with up-to-date Lightroom Classic.

The exact Lightroom Classic build numbers and the preset’s numerical Color Mixer settings are not included here because I have not verified them for this report.