Issue with joining two query_results on dates

Hello. First time poster so please excuse and educate if I misstep.

I have two separate data sources that I import, in this example a is from a google sheets connection and b is from a PostgreSQL connection, and I’m trying to join them using query_result.

The query_result of a:

The query_result of b:

Both return some kind of date format and they appear identical. But as you can see, joining them returns nothing:

The syntax for the join is copied from here: user-guide

SELECT
a.eventdate,
b.eventdate
FROM query_709174 AS a
JOIN query_709139 AS b
ON a.eventdate = b.eventdate

Any ideas why I’m not able to join these two queries using query_result?