Search result incomplete, esp. with date constraints

[pjb]

I know there are similar topics, such as

Runbox 6 -- Searching for emails with or without Current Folder option is not functioning correctly

KEY NOTE: The following is relative to Runbox Version 6 -– (this version works better than 7 for me) Search by email and Current Folder do not function correctly or at all TWO main issues: When performing a search for a specific email address – particularly when the email is recent – does NOT show up in the list of results, even though the email address specified matches the query. When using the search function, whether it be using the “From” or “Entire Message” option,…and whether it’s…

Anyway I want to raise another problem: Search results are clearly incomplete. Consider following screenshots.

It is supposed to work like this:

But this doesn’t work for me. In following screenshot at least one more message should appear:

Even more incomplete when using a bracket:

And range search also defect:

This applies to both RMM6 and RMM7, with former seemingly to perform somewhat better (more complete in one of three queries, but this may be random).