I’ve had a few that didn’t want to work on my first try installing them until I reseated them even though they looked like they were installed properly. So I would just try some tape, better than throwing away the whole server. Just insert the m.2 male sure it works and then put tape from where the screw is to all the way behind the connector, basically putting some pressure on the m.2 towards the connector.

Could it be the vibration of the HDDs, if you say a re seat fixes it they might come a bit loose. Maybe try using some tape or hot glue to hold them in place?