So I am a DM on delta and decided to go SDC on an earlier flight yesterday from ATL to FLL. I was confirmed sitting in an EC aisle seat and decide to visit the SkyClub in terminal E for some biscoffs and a vodka soda. While enjoying my drink i decide to check how im doing on the upgrade list on my fly delta app and much to my surprise i see i have no seat assignment. I walk over to the SC agent and ask "what gives?" The agent's response, "Sorry, must be a EQ change the only seat open is 45A." Ends up the first class cabin checked in full so no upgrade and I sat waayyyy in the back and got off the plane 30mins after reaching the gate. Anyone else ever have this happen to them? And I'm pretty displeased with how Delta handled this with pretty much a TS response.