I don’t seem to get this to work; applying a custom preset to multiple selected images (or even one for that matter).
I’ve created a very basic preset consisting of the default optics correction, then DeepPrime and saved the settings as a preset
When I apply this preset manually from customize it does what I expect, enable DeepPrime on top of the optics correction.
When I apply this from the image library, nothing happens.
This should be basic, It should for instance be possible to take a photo of a gray-card. Then in post take this image to set white-balance, save it as a preset and then apply it to all (selected) images in a folder in the image library.
In addition to what @Wolfgang said, you have to select all the images that you wish to correct using Shift+click(in Windows) and then apply the preset. Better yet, just set your preset as the default preset for all RAW images.
For your WB question, apply the correct WB to the gray-card shot with the picker then copy the setting, select the files you wish to correct, as above, and paste the selected corrections to your chosen images.
If you select at first the picture as the source for your WB adjustment (in the customise mode) and add more pictures to the selection, the white balance change will affect all selected images without copying the settings. PL is very good at synchronous editing of a selection of files. Even the automatic function of, say, microcontrast will apply to all selected images - BUT not with the value of the first image. Instead each image gets it’s own auto-adjustment value.