Copter 3.5.2 Compass Drift

Recently updated the Copter Firmware from 3.5.1 to 3.5.2. This is being flown on an S1000 octocopter frame, Pixhawk 2, and laser altimeter. After successful calibration of compass, noticed large compass drift in the order of 180 degrees over the course of 2 or 3 minutes. Calibration was further done with external compass only, internal compass only, and both compasses. This high drift was still shown after replacing the U-Blox Neo-M8N with a spare and moving to a place of no known interference. It appears that the only variable that changed between the compasses working and not working was the update to 3.5.2. Has anyone updated firmware to 3.5.2 and come across this? Thanks