Do flaked grains (rye, oats, wheat, etc.) at 15% cause a beer to be cloudy?
I can get beers to clear just fine with that amount of flaked grains. Unless a powdery yeast strain is used (wit yeast, hefe strain, etc).
I have also had things that are approaching 20% flaked content that end up totally clear at the end. I did one that was 20% (12% flaked barley and 6% flaked oats) and that came out totally clear after a little gelatin was used to speed up the process. I commonly have things in the 10% area and they are all brilliantly clear.
Nope, not on their own.
In an extract batch without any base malt to convert the starch, I would say yes, it’s likely.
I use 50% flaked wheat in my wit and it starts out cloudy but it’s usually crystal clear before I finish drinking a batch.
Gotta rock the keg now and then. If it bothers you.