OK - here's a log.txt file from a flight just now + another screenshot showing the interior rain. Contrary to my previous comment that it only happened in the lower left screen quadrant the raindrops move with the view i.e. if you move from the left pilot seat to the right the interior raindrops move with the view.
Weather conditions in this shot are set manually to heavy rain
Actually - there don't appear to be any raindrops on the outside windscreen. The raindrops in the screenshot are all inside the cockpit. What it looks to me is happening is the raindrops which should be drawing on the widnscreen outside are instead showing up inside the cockpit and in front of the instrument panel/glare shield
Log.txt