Legacy issues with 3 separate tracks

I suspect either incomplete isolation between the loops or a phasing issue.

Disconnect your power leads from the track.  Use a multimeter to verify that the center rails of loops 1 and are isolated.  If there is any connectivity, examine the insulated pins (or whatever you are using) to look for any connection between the center rails of the loops.  Once you are sure  that the middle rail of the loops are isolated, connect the power leads with the power off.

If the tracks are isolated  - good.  Turn on the power and set both loops 1 and 2 to the same voltage.  Measure the voltage on the center rails across the gap.  I should be 5 volts or less.  We're looking for a phasing issue here.  If you see a high voltage, change the power feed to one of the loops and test again.