Created attachment 108945 [details] screenshot open dolphin right click an ISO disc image file select some action (I tested "burn disc image with k3b") back to dolphin, open another location using the same dolphin window/tab back to folder where your ISO file is placed clicking on left arrow on upper left corner My acreenshot shows the wrong icon. The icon becomes correct after press F5.
Breeze dark is affected too. Reproducible on Arch Linux (plasma 5.11.3) and neon dev unstable.
I don't know if this is an icon fix, I think no. So maybe someone else can help.
Maybe (?) a dublicate of the https://bugs.kde.org/show_bug.cgi?id=337035 and the upstream bug: https://bugs.freedesktop.org/show_bug.cgi?id=80877
I doubt it's an upstream bug. I have Arch + Gnome 3.26.2 installed on another computer and I noticed no problem between nautilus and ISO files so far.
Looks like it's an upstream bug, and the discussion upstream never reached a conclusion regarding how to fix is for us (due to technical implementation details, it doesn't affect GNOME's Nautilus file manager). *** This bug has been marked as a duplicate of bug 337035 ***