Am I being undermined as the new CEO because I'm a woman or am I imagining it?

Probably both. Kris Kluver, in The Dysfunctional Family Office, has Gail Mitchell name this directly without flinching. For some old-school men in legacy industries, there is a double standard. A man in the same position is considered authoritative. A woman in the same position is questioned, second-guessed, or quietly bypassed. The double standard is real. It also doesn't account for everything. Some of what feels like sexism is genuine resistance to any new CEO regardless of gender. Some of it is sexism layered on top of that resistance. Sorting which is which doesn't change the response. The fix is the same in both cases. Set clear expectations. Enforce them consistently. Replace executives who can't or won't adjust. Build relationships with peers who get it. Don't let the doubt about whether it's really sexism become a reason to delay the structural moves the role requires. Chris Richardson works with rising generation women CEOs on this exact navigation at thethirtyadvisors.com.