Here are our membership rules, they seem ok. We're using CiviCRM 5.58.1 with Wordpress. After a recent set of upgrades we are experiencing an issue where current members who are renewing their membership are now flagged as new members after renewing. My guess is that this is as a result of Civi being unable to match the fields correctly. Is anyone else having this issue and do you have any suggestions as to how to resolve the issue. Thanks!
When you say they're "flagged as new", I assume you mean their Membership Status field is marked "New".
If so, then someone has probably configured the membership statuses incorrectly. Go to Administer menu » CiviMember » Membership Status Rules. My guess is someone has modified the New status to use Start Date and not Join Date.