There are a lot of limitations with the TIS. It is available from some approach radar sites across the country; mostly just around large cities. The radar sweeps every 5 seconds and then sends out the info to the TIS on the next sweep. So the information you are receiving is at least 5 seconds old. That’s why if you are doing steep turns or other abrupt maneuvers you will get a traffic alert at your position and then it will go away. The TIS does try and predict what the “intruder” is doing, if the “intruder” is straight and level it will do all right, but with VFR maneuvering it doesn’t really do too well.
Also the “intruder” aircraft must have an operating transponder for you to receive an alert. So if some VFR guy was flying with his transponder on stby he would not be reported.
The TIS also becomes more unreliable the farther away from the radar facility. If you’re more than 30 miles the TIS will report traffic with up to almost a half-mile error.
I’ve been telling my student not to rely on it and use it as a backup. When a target pops up they should try to find it but they must keep in mind there might be other aircraft that aren’t on the TIS.
You can turn the traffic alerts off. In the map page there is a TRAFFIC soft key that will turn the system off. I’ve never encountered what you are talking about though; there may be something wrong with the system.
If I’m wrong on some of this info please someone let me know but this is my understanding of how the system works. Hopefully I got it right.