It's not specifically a 105 or even a Shimano problem. Any modern 2x drivetrain installed on a bike with short chainstays will have some issues in the small chainring and smallest cogs. The chain angle necessary to reach from the small chainring to the smallest few cogs at the rear will cause some contact with the large chainring. There is no amount of tuning that will get rid of this, short of altering the parts involved.