Weird artifact with Path Traced glass

Hey

While using Path Tracing I noticed weird artifacts on shadows casted by glass. Do you guys have any idea on what could possibly cause such issue? I tried all types of glass materials for Path tracer (the ones put in official PT docs) and it just won’t disappear. Found it disappears only when turning off Approximate Caustics, but then the glass gets really dark and its just not how it should work.

Also, the mesh is all fine - I made sure its all welded, smoothed, has no issues with normals whatsoever - works with 3ds + Corona.

Attaching a screenshot showing the issue:


Much appreciated