Unable to activate UI elements from other blueprints

I’m making a card game and I’m running into some problems that are becoming extremely frustrating.

I have certain events set up to randomly draw a card from a deck, and I want the UI to reflect the card that is drawn. I have individual actors for each card and I have the images set up in the UI that reflect each one. However, the only way I am able to make the UI elements appear is within the UI blueprint script, though I want to make them appear as part of the script I use when it draws the card. I have visibility variables set up in the UI script but any time I try to change them from a different blueprint, nothing happens. They require a target input, and I have the UI set up as the target, but again, nothing is happening. On a related note, in the variables section of separate blueprints, the variable that I’m using to reference the UI (to plug into the target input of the visibility variable) appears as a hollow circle instead of a sphere, like most other variables. I suspect this might have something to do with the problem but I can’t figure out what needs to change. Please help. I can provide screen shots if necessary.