Put the summary of the bug you're having here

I expected to see the outline around the player in the inventory if the player has the glowing (=Spectral Arrow) effect. The player has no outlines in the inventory.

Steps to Reproduce:
1. Get shot by a player with a Spectral arrow or type /effect @p[r=3] minecraft:glowing 10 0
2. Open your inventory and look at the player preview which usually shows armor etc.
3. ...