I've been having trouble with applying my ui as a texture in the material editor. I even tried to use the legacy material editor, but it always appears completely clear whenever i apply it to a mesh. I'm really not sure what to do.

Are you trying to apply an UI on a plane? There is an FG node you need to activate under the UI node section.

Entity:FlashInvoke. Set method to vPlay and drag your entity to Choose Entity.