P: When changing presets the profile resets back to Adobe standard, even if profile isn't checke

Yes preset stacking IS valid and CAN be done as long as NONE of the sliders cancel out each other. so if 1 preset is Highlights +10 and the other Preset is Sharpen -10 you CAN stack those fine. Many teachers (Ben Willmore, Jared Platt, etc) have created a hundred presets for their class students that work this way so that they CAN be additive and they break down a preset into its small individual components. Many presets out there do TOO MANY things all in one sweep but to be more effective many create presets that are smaller single area adjustments instead of affecting all panels at once. so yes this still needs to work as before otherwise there will be a LOT of unhappy Lr users out there...

Thanks Rainer, the engineers are on it.

Hello Victoria, i can reproduce the issue with raw.
I have Nates X-Chrome presets. In the presets-film section, there is a camera profile included (Nates Pure Tone camera profile). The 2nd section is X-Chrome developers and 3rd section is X-Chrome tone+paper.
And there the raw changes back to color.

Rainer

Sadly this does not work on many presets because any mod preset that does not define a profile (for example an exposure preset) will simply revert to color and if a profile is defined in such a preset it will stay black and white but the Black and White adjustment sliders will be reset to zero.

Do I need do this to all my around 100 saved presets? Or is it really bug and will be fixed soon?

Watch this forum (upper), its a bug - try this, maybe it will work for you:
1. use one of your old B&W presets (Adobe Standard BW profile)
2. change profile to one of 17 profiles in BW section (not Monochrome)
3. set amount of profile effect to zero (0%)
4. update your preset

We are sending a newsletter and making blog posts warning people to not update to Lightroom 7.3 until this is fixed. If anyone finds a working workaround please advise.

@7789253. Thank you for this update. I am very grateful to hear the news and eager for the update so my workflow is operational once more. ESPECIALLY for the API fix for midi controllers please!
Thank you.

My edited photos that are BW are converted back to color when I use my saved preset that edit for example just grain or sharpness and no colour changes. Is it bug? Happen after latest update. Thanks.

I tested this every way of sunday. Your apprach works from what I can tell if the preset uses new black and white profiles. But if you have a presets from last week that convert to black and white and then apply a new exposure presets using the paramaters you mention, the black and white slider are reset. At least on mine.
 I would love to find a working solution.