The 787 (BOE214) out of CHS is a Boeing B1 or C1 flight. The B1 is a Boeing flight (Boeing test pilots) just after production from the Charleston factory and is the first flight to test all aircraft systems. Once the B1 is complete the Customer airline sends their Technical Pilot or another experienced Company pilot to fly the same profile which is a C1. Each flight takes approximately 2 to 2.5 hours. These flights are conducted off the South Carolina coast in a race track pattern as shown on your FR24 image. From memory this area is also part civil and part military airspace.
Not sure what the BLOCKED airplane is, but might be military!! Who knows.
Dog