I believe the issue was simply that the index table was probably not recreated when it's configuration was changed. So I simple clicked the 'Create new index' button, and now it looks like it's working.
I have also changed the logic to AND, for testing: https://i.imgur.com/lG6ZzMP.png
Now if I type in for example 'chelmsford plumber' I get only matches where both of these keywords are present – likely from their categories.Best,
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