Bit of a strange one.
Playing today, had just placed a new HART base and given it a custom icon, I had noticed that a vehicle I had just sent on patrol was not showing on map, but was showing as status 1 in the building menu. After a refresh all custom graphics were missing entirely. Mission Icons, Building Icons and Vehicle graphics both manually uploaded and from packs.
I was using LSSM V4.0 but this issue persists even after removing and reloading, clearing cache/cookies, rebooting PC, etc.
However! using a different profile on same browser (Chrome) it works fine, and works fine on mobile.
1st image is how my graphics normally look.
2nd image is how it currently looks.