There seems to be a limit as to how many keywords can be shown in the scrollable keyword list. I can no longer scroll down to the end of the list. This wasn't a problem in LR5, mostly because all my keywords had to be added by hand and so there weren't that many. With LR6 adding bunches of 'faces' to my 'people' keywords I'm hitting a wall. If I collapse 'people' then I'm fine. If I expand 'people' I can only see the first 2/3 of them.
Does anyone know of a work around?
There is a Windows bug that limits any scrollable list to about 1600 items. That may be what you are seeing. There is no known limit to the number of keywords you can use in Lightroom.
The solution is to use a hierarchical keyword list, so that there's never anywhere near 1600 items to be shown at any one time. Even if there are 1600 under people, you could still put them into family hierarchies, or other hierarchies.
Thanks dj_paige. I didn't think I had nearly that many but I'll look into breaking them down into smaller groups anyway.