sorry I cannot help, but I just encountered a similar problem and would be interested in the solution:
I used to have the keywords in alphabetical order. Then I tried to add a new keyword, but once I clicked the OK button of the pop-up dialog, the new keyword didn’t appear in the list. So I added it manually to the end of my .bib file with a text editor. Now my keywords are no longer sorted alphabetically
Is there any way to restore the order (apart from doing it manually)?