Your software
My Mautic version is:2.16.0
My PHP version is: 7.2.27
Your problem
My problem is: where are contacts that are not associated with any segment, stored? Or are they simply known as not associated with any segment and that’s that?
How can someone search for ONLY contacts not associated with a segment? There doesn’t seem to be a way to filter and separate out contacts not associated with segments vs. those associated with contacts. .
I couldn’t see anything obvious in the search filters that are available, I’ve asked in the dev channel on Slack.
Depending on how many segments you have, it might be possible to chain negatives (e.g. !segment + !segment2 + !segment3) although that would rapidly become unmanagable.
I’ve had the same issue. The only way I’ve found to identify these kind of contacts is using an external database query, then using Mautic’s API to batch update the contacts - I personally put them into a segment called “no segment”, but you could do whatever you want. Let me know if you want more detail.