First, I want to say that Krita is an incredible piece of work, I appreciate the developers! I have already started donating and look forward to helping in future.

I am using it on Mac OS 10.14.2. I am struggling with using the color dockers. Five of them (Advanced Color Selector, Small Color Selector, etc. etc.) all have the same problem. After using them to choose a color, the brush stops working. Occasionally it recovers after 20? seconds, but most of the time, it never does. To recover the brush functionality/cursor, the best solution I found is to immediately go to the main tools bar, select any tool, and then hit B (the shortcut for brush). That seems to work every time. If there is a quicker way to do this (e.g., some kind of keyboard action), I'd love to know as it would hugely improve my efficiency.

The one color docker that doesn't have this problem is Palette. I am able to select swatches in the Palette, and then there is a quite brief, but noticeable delay (< 1/2 second), and the brush works again.

The keyboard shortcuts for color adjustments (e.g. K and L for darker/lighter) work instantaneously. Also, P for eyedropper, and O/I for opacity adjustment work reliably too. So currently, my best option for working with color seems to be using the Palette, with keyboard shortcuts for fine adjustments, and also mixing colors on the canvas.

Thanks for any tips on workarounds I may have missed so far.

One more color tool I found is the one in the Pop-up Palette. This does not break the brush, and is a good substitute for the Advanced Color Selector, so I'll probably use it a lot.

I also found it useful to set up keyboard shortcuts in Preferences for (under "Painting") saturate/desaturate, add more blue, add more green etc.
But I am wondering if there is a way to control the size of the increments for these things (also K/L for darken/lighten).

No, you cannot change the increments. As for the original issue, it's too warm right now for me to setup my macOS test system, but I'll try to reproduce next week. If it's reproducible, we'll need a bug report, and I'll bug Ghevan to work on it

Thanks. At first I thought you were using "developer's slang", then I remembered the news about the European heat wave. Good luck with that!

Yes, the weather conditions are rather uncomfortable right now