Strange Circle Appears in Substance Painter Iray After Camera Adjustments (v10.1.2)

Issue:

A strange circle appears when rendering in Iray as soon as Caustic Sampler is enabled. The issue persists after restarting the software and accross projects. 

What Makes It Worse:

• Increasing the field of view makes it progressively more visible.

What Makes It Better or Removes It:

• Lowering the field of view reduces it, and at the lowest possible FOV, it almost disappears.
• Switching to orthographic view removes it entirely.
• Enabling clear color makes it go away.
• Disabling the caustic sampler completely removes the issue.