The answer to 'why is my gutters missing shingles' is that the shingles on your roof may be damaged or deteriorating, causing them to fall off and end up in your gutters. This is a common issue that can occur due to age, weathering, or improper installation of the roofing system.
Symptoms of this problem include missing or loose shingles, debris in the gutters, and water leaks or damage around the roof. Solutions may involve repairing or replacing the damaged shingles, as well as cleaning out the gutters. If the issue is widespread, it's best to have a professional roofing contractor inspect the roof and provide a comprehensive repair or replacement plan.