Ecto.Adapters.SQL.query! gives a different result - postgresql

Question

So this is apparently one of these weird days... And I know this makes 0 sense.
I'm executing a query in datagrip (a tool to execute raw querys) to the exact same database as in my phoenix application. And they are returning different results.
The query is quite complicated, but it's the only query that shows different results. So I cannot simplify it. I've tried other queries to be sure that I'm having the same database, restarted the server etc.
Here is the exact same query executed from my console. As you can see it is not the same result. A few rows are missing.
I have also checked if this is a timing issue by executing select now() => same result (more or less obviously). If I execute only the generate_series part, it returns the same result. So it could have something to do with the join.
I also checked the last few entries in the ttnmessages table just to be sure there is no general caching issue. The queries do also give the same result there.
So my question is: Is there anything that Ecto does differently upon executing a query? How can I figure this out? I'm grateful for any hint.
EDIT: The query is in both cases:
SELECT g.series AS time, MAX((t.payload ->'pulse')::text::numeric) as pulse
FROM generate_series(date_trunc('hour', now())- INTERVAL '12 hours', date_trunc('hour', now()), INTERVAL '60 min') AS g(series)
LEFT JOIN ttnmessages t
ON t.inserted_at < g.series + INTERVAL '60 min'
AND t.inserted_at > g.series
WHERE t.hardware_serial LIKE '093B55DF0C2C525A'
GROUP BY g.series
ORDER BY g.series;

Answer 1

While I did not find out the cause, I changed the query to the following:
SELECT MAX(t.inserted_at) as time, (t.payload ->'pulse')::text::numeric as pulse
FROM ttnmessages t
WHERE t.inserted_at > now() - INTERVAL '12 hours'
AND t.payload ->'pulse' IS NOT NULL
AND t.hardware_serial LIKE '093B55DF0C2C525A'
GROUP BY (t.payload ->'pulse')
ORDER BY time;
Runtime is < 50ms, so I'm happy with the result.
And I'll ignore the different results from the question. The query here returns the same result just like it's supposed to.