Suddenly (sometime since December) when I am using polyscope and turn off Autocontour, either on the plane or on the strips, I end up with only one positive contour level showing, almost no matter what settings I enter into the contour parameters dialog box. I open the same spectrum in sparky, like how the spectrum looks with the threshold set to 3e+09 and factor 1.4, try those same parameters in cara, and still get just a single contour.
Not being able to control the contours is really causing difficulty for analyzing spectra.
I've tried this on the NMRbox installation of CARA, the new one you posted today, and also cara_1.8.4_linux on NMRbox. I've also tried it on RHEL 7, cara_1.8.4_linux, and on mac os 10.11.6, both cara_18.104.22.168_mac and CARA 2.app