conversation.last_post_time not working?

Hi,

I'm trying to use conversation.last_post_time as a constraint in a query but I'm not getting the expected results.

The documentation says it can be used as I constraint: https://community.lithium.com/t5/Developer-Documentation/bd-p/dev-doc-portal?section=commv2&collection=messages#constraints

I want to pull a list of threads that were last active during a period of time to archive them, so I'm using this query:

SELECT id, board, conversation, view_href, metrics, post_time FROM messages WHERE conversation.last_post_time <= ${endDate} AND conversation.last_post_time > ${startDate} AND depth = 0 AND board.id='${board}'

It seems to work, but I'm doing some tests and the results are not accurate. For example

If I use this query:

SELECT count(*) FROM messages WHERE conversation.last_post_time <= 2011-09-18T23:59:59-07:00 AND conversation.last_post_time > 2011-09-18T00:00:00-07:00 AND depth = 0 AND board.id='ArchivesImprimantes'

I get zero results. Here's the screenshot of the response when using API 2.0 directly on the production community on the browser

But I know there's a thread that meet the criteria. This is the thread information I get when using the same API 2.0

It would seem as is the query is ALSO checking the original post date and matching it to the daterange. But I don't care about the original post date, I just need the last_post_date.

Can someone confirm the actual behavior of the API call? Am I not understanding the documentation?

Thanks!