Multiple Billboards causes graphical glitch

I’m having some troubles with using multiple Material Billboards in my project, during split-screen play. At the start of play, I have a number of vehicles spawn in to the game dependant on the number of players. As the vehicles spawn, an additional actor with a Material Billboard component (with a crosshair for the material) is spawned in. These ‘crosshair’ actors then have their locations updated depending on each player’s selection of ‘target’ (they can switch through all enemies and set them as the targets for the crosshair actors).

I have each crosshair actor set to have “only owner see” enabled, so that each player can only see their own crosshair on other vehicles.

Player 1’s crosshair actor displays perfectly fine, every time. Any additional players get all sorts of glitchy displays for their crosshairs.

I don’t know much about the rendering side of UE4 so I’m stumped. I tried looking for help here before posting but could only find 1 entry, which states that a similar issue was already fixed in UE4.22…

I have attached screenshots to hopefully better explain my situation

Any and all help is appreciated!