As was noted in
this SLP interview, Inklings Press does some AH short fiction. I've seen AH stories appear in several pro-rate sf magazines such as Clarkesworld, Asimov's and Analog, although the competition for pro-rate short fiction is obviously pretty stiff.
Although I'd add a cautionary tale that despite listing themselves as open to AH, there's still plenty of markets which don't really get it. Without naming any names, I recently had a polite rejection for an AH short story for an anthology which described itself as open to AH. They included their slush reader feedback - which complained that my story didn't reflect the history of the country it was set in,
without realising that it was alternate history. The lesson I took from that was to make the divergences much, much more explicit and obvious when writing for an audience outside of the AH online subculture.