Mac Client - Maven and some rituals covered in black boxes

Hi All,

I'm encountering a bug loading/view Maven and some rituals. Instead of showing Maven I just get a black box where she is on the screen. If I run around the box moves but I never see Maven. This also occurs on some rituals though it often goes away as mobs die. I have not seen this bug anywhere outside of Maven or rituals.

System Specs - currently playing through Steam.
iMac (27-inch, Late 2013)
Processor 3.5 GHz Quad-Core Intel Core i7
Memory 16 GB 1600 MHz DDR3
Graphics NVIDIA GeForce GTX 780M 4 GB

Thanks!

Also adding more details - installing and using standalone client did not fix. Images below showing both Maven and ritual covered by black boxes.