I am using Engrave - Paragraph Styles - “Bar Numbers (Parts)” and change the Size. No matter which option enabled (staff-relative or absolute) the bar number sized do not change in the single parts view.
They only change is happening when I use “Bar Numbers (Score)” Size. But this option should only change the Bar Numbers size inside the Full Scores, right ?
Layout Options > Bar Number. Set Paragraph Style (top option) to “Bar numbers (part)”
This is probably set by default for projects created since Dorico 2 was released, but for older files you’ll need to do it yourself. Bear in mind that you can shift click all of your parts in the left column of Layout Options and change them all in one go.