Useful update in the comments section of the video linked in post #62.
UPDATE: 6/6/23 ATC Audio Timeline:
1722:22Z N611VG checks in with Atlanta Center (ZTL) at FL230 and issued a climb to FL290 which was read back correctly.
1725:50Z ZTL issues N611VG a climb to FL340 as the aircraft was passing through FL277. This clearance was acknowledged and read back correctly.
1728:33Z ZTL amends the altitude to FL330 because of traffic in the next sector in Washington Center’s (ZDC) airspace. N611VG was passing through FL320. This transmission was never acknowledged and ATC was unable to contact N611VG again.
So somewhere between 1725Z and 1728Z (Shortly after takeoff, while climbing out) the event occurred that caused the remainder of the flight to out of contact with ATC. Jb.