I've created a duplicate of the equipment menu to use for an outfit system. It uses the UI Box Blue Menu Top Scroll with an added sprite portrait component.
When the menu is opened from the overview menu it correctly loads the selected character's equipment.
(A separate attached HUD loads their prefab portrait without issue.)
However the sprite portrait component attached to the equipment box doesn't load the portrait first time.
The sprite portrait shows as the default blank white image (I unchecked the disabled if empty tickbox for testing.) Unless I scroll down through the options or cycle through the other combatants. It will never load first time, as though it doesn't know WHO the combatant is even though the same menu correctly loads their equipment.
In the second shot I simply pressed the down arrow to select slot two and it refreshed and drew the portrait. The same happens if I cycle to another combatant. It doesn't matter which combatant I select first the portrait will not draw until something forces it to refresh.
The menu uses these settings: From the Overview Menu
The Outfit Menu (which is a modified equipment menu)
I'm not sure if I've configured something incorrectly or if it is a bug but I cannot get it to load the portrait first time unless I either switch combatant or move the cursor up and down through the menu. Portraits work fine elsewhere within the project and the portrait type matches that of the prefab.
Since your menu screen is set up to show the user's portrait, all you need to do is add a UI Portrait component setup to it that's referenced in the UI Box component's portrait content (e.g. easily via the scene hierarchy context menu).
Your current setup seems to have a HUD set a portrait, but since the HUD will not have any content do display, it'll not show a portrait.
If you're enjoying my products, updates and support, please consider supporting me on patreon.com!