The "Ghost Filtering" uses an algorithm to exclude yourself, "the ghost" from the traffic screen.
This is achieved by trending your aircraft speed, direction, altitude, etc and then comparing it to that nearby traffic target. When at cruise on a cross-country, this filtering works well. However, when you start making steep turns or aggressive altitude changes, the algorithm starts to break apart and can prompt a traffic alert.
Being that you do not have ADS-B out, it's somewhat laggy as we are trying to filter your Mode C or Mode S target. We are also looking at additional ways to filter based on an aircraft number, ICAO, etc, but this is limited when an ADS-B Out is not present.
Currently, I believe we are much more aggressive on Ghost Filtering or reducing Traffic Alerts when inside the Traffic Pattern. Otherwise it would be going off all the time. We are continuing to work with pilots and ADS-B partners to reduce these "known" ghosting issue. It's inherent to the ADS-B system, at least unit more have ADS-B out and ATC starts using ADS-B as the primary report. I hope this helps.