GA pilot conducting a practice RNAV 25 Approach to I19 airport reported CMH TRACON advised them they were off course even though multiple aircraft navigation sources and visual cues indicated the aircraft was on course. The reporter believes TRACON's depiction of fixes on their radar display may be erroneous.

Narrative

Columbus Approach cleared aircraft for practice RNAV 25 approach into I19 (Greene County) via direct PODIY at 3;000 feet. At about 1 mile from PODIY ATC inquired if the aircraft was heading to PODIY; reporting that we were tracking almost 50 degrees off direct heading according to the ATC radar. The aircraft is equipped with and was using WAAS based ADS-B out. This was in-conflict with multiple GPS sources in the cockpit and I elected to continue the approach based on in-cockpit indications which all agreed from the panel mounted Garmin 300XL; 2 tablets running 3 different EFB apps on current chart cycle; and out the window visual position reported by my safety pilot. The 300XL reported the approach armed without a RAIM discrepancy. Upon passing PODIY as indicated by the cockpit indications; ATC reported PODIY as being about 2 miles SE of our current position which puts the ATC position south of SGH when all approach plates the pilot looked at show PODIY north of SGH. Upon approaching the next waypoint of TUNNU; ATC gave a distance countdown to the waypoint which matched the 300XL position from the waypoint exactly. The rest of the approach continued without incident. Recommend an investigation into Columbus Approach's depiction of PODIY and confirm it is in alignment with current approach charts.