I upgraded to a wide gamut monitor for my photographic work and calibrated it with DisplayCal (default profile settings). I ditched FastPictureViewer because it's more or less abandonware and quite buggy at this point.
The DO12 Image Viewer has color management, but unfortunately it doesn't work with my monitor profile. sRGB images look oversaturated in DO Viewer, while they look fine in Photoshop, Lightroom, IrfanView, Firefox and Chrome. Color management in DO is set to use the specific .ICM file that all the other apps use through Win10, but DO doesn't apply the profile to the images, even after a PC reboot.
Color management support is currently fairly limited and only covers the situations mentioned in the documentation for the Prefs > Miscellaneous > Advanced > use_color_management color management setting (on this page).
I'm aware of that, but i am within those limits. It still doesn't work. I tried now with two different monitor profiles. The first one was a combined LUT+Matrix ICC profile, the second one was Curves+Matrix (that's the one recommended for compatibility).
I could send you the two profiles to take a look, if it helps.
UPDATE: Weird thing. I profiled my monitor again, because i wasn't quite happy with the colorimeter correction. I'm pretty sure that the only thing i changed was that i enabled black point compensation for the Curves+Matrix profile (as per suggestion from DisplayCal's author).
Now the profile seems to work in DO Viewer. I'll send it your way, so you could check it out.
So, after testing some more, it's working now - even with a LUT+matrix profile. I can't reproduce the issue anymore, and i'm confused why it happened in the first place. A possibility could be that i stumbled upon some images without profile and since DO12 can't color manage those, it could've thrown me off.