I have found a few odd cases where the phrase suggester with suggest_mode: "missing" generates a suggestion even though the query returns results. I am querying across two indexes but the query term only exists in one of the indexes. I get the search results I expect, but I do not expect to get a suggestion.
I am trying to come up with a curl recreation but I haven't been able to reproduce it yet in a smaller corpus.
I believe what is happening is that the phrase suggestions are getting merged together in the same way the query results are merged together across multiple indexes. If I have query results from test_1 and no results from test_2, then I expect to see results from test_1. But if I have a suggestion from test_1 and no suggestion from test_2 (due to suggest_mode: "missing"), I do not expect to see a suggestion.