The marker icons of gear and/or dynamic icons cannot be apllied to non-gear (weapon/armor) items.
You need to disable the "research check" at the icon's settings:

Go to Settings->Addons->FCO ItemSaver->

Dynamic icons
ICONS -> DYNAMIC ICONS -> DYNAMIC ICONS -> 1st DYNAMIC (or whichever one you want to change) and turn on "Disable armor/weapon check" (Old description until 03.2018 was: "Disable research check").

Gear set icons
ICONS -> Gear sets -> 1st Gear (or whichever one you want to change) and turn on "Disable armor/weapon check" (Old description until 03.2018 was: "Disable research check").