Looks like you solved it? It works for me at least right now.
Yes, posts related to undefined field are ejected. It's a complicated problem. Initially I was planning to add an option called “Show result if the field is not defined?”, but I had to remove that. The resason is, that it's impossible to distinguish if the field in question is not matching or not defined on database level. It resulted showing every result despite they were not matching the custom field criteria, because they were recognized as not defined.
Then I tried different approaches, but all of them were dismissed because of the huge performance impact.Best,
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