Xerath gets a Blue square for his Passive instead of the image

Xerath gets a Blue square for his Passive instead of the image

I have had this happen on at least 3 separate occasions. I have not been able to determine any logical cause for it For the entire game sometimes it just appears as a blue square both in the passive box, and where it shows above his abilities.

Note: it still works correctly, and when it goes on CD, the numbers (time left on CD) appear through the blue, then disappear when it comes back off CD. Minor inconvenience, but annoying.