She has never been kept with a heat source - this ulcer is likely caused by her very large abdomen constantly rubbing on the substrate and other items in her enclosure. I got this girl already with this ulcer present. In my experience, you can't correct this and can only prevent it from worsening.
This girl finally moulted and I have confirmed that she is female. She was purchased as unsexed last September and moulted today for the first time with me. She was pricey, so I took a gamble, but I have no regrets.