Bug: Cannot find the last plague heart in Providence Ridge

[P34nk]

I'm in the Dread Zone difficulty, second playthrough with the Trader legacy (from first one), with one survivor from the first game (Started fresh on first one). I have 8 survivors, and it looks like I'm stuck with the last plague heart (6/7). I drive to every corner of the map/buildings with survey car, and no plague heart. I do not have any radio options to check the location of the last heart.
Any suggestions? I have a few survivors I would like to keep for the next one. Is there any solution besides changing maps (if that will resolve the issue)?