Fellow DL flyers,

I am in the process of trying to book some DL flights to Seattle from CVG in mid / late may and am having difficulty in finding availability. I've also seen this on other times and legs. Is Delta limiting the sell of coach / C+ seats domestically for some reason? When I look at seat maps, they are mostly wide open. Now, I know that seats may appear in the map that is not representative of flight load. I am finding if I call DL there seems to be availability, but through their app and website, there isn't. Perhaps there is a conference or cruise ships for that timeframe? Or maybe DL is anticipating schedule and equipment changes and therefore blocking out any coach / C+ seats for purchase? Or maybe it is my cookies allowing DL to try and upsell?

Unfortunately, I am forced to book business trips using Egencia which seems to hate Delta. I am trying to stay loyal, but if there is nothing to buy, how can I?