Can you link the specific items that are not able to be stored in the Armoire that have the Armoire icon lit up? This does not seem like enough information.

If items can't be stored in the Armoire, then usually:
  • It can be bought again from either a Calamity Salvager or another NPC (such as Tataru's friend, or the person near The Ondo Cups).
  • It is crafted gear and can be crafted or bought from the Market Board.
  • It is tomestone gear and can be bought again with tomestones or hunt currencies.
  • It is raid gear and can be obtained quickly by getting the coffer drops from the raids.
  • It is dungeon gear and can be farmed for.
  • It is mog station or old seasonal event gear and can bought on the store again, or may be available in the seasonal event category of the Calamity Salvager.
Any other gear can be put in the Glamour Dresser anyway, which has 800 slots.