It's just laggy sometimes. Compositions will spawn first, then other players and AIs and only then your inventory items will show up. It's annoying and something should be done about it, but your items will load in eventually... sucks when the base you chose is overrun with unfriendly troops who cannot capture it (enemy beyond HQ signal, or just FIA). If all the AIs are dead, there is literally no warning that there's enemy in the area before you deploy.