stereo not panning fully

I’m using Cubase 9.5 and am creating a backing track. I need complete stereo panning to place the click on the left side and the track on the right side. I have panned both things fully but am getting a bit of the click track through the right side.
Is there a reason why panning the click completely to the left still leaves some in the right channel? Is there a way to fix it?
Thanks very much for your help.

When you export the file, do you also see it in the waveform?

Could be a lot of factors. M/S-EQing in the chain/on master, Control Room on & both CR out and Outputs routed to your monitors, hidden & forgotten tracks that are playing invisibly in your project…