@lgerkin I found a few links that may be of interest. One of them suggests that malfunctioning SI joints can also contribute to a problem like this. I know that my pelvis goes out of alignment because of the SI joints and my physical therapist assesses and adjusts this, so you might ask your therapist if your pelvis is aligned properly and if it stays that way or shifts.. The others are about case studies of a similar problems. The link from MSK Neurology explains problems that can contribute to similar symptoms from other sources. I realize your imaging shows calcification of tendons. It may be possible that your pain is coming from more than one source, so it may be work asking if there is also any nerve impingement between tight muscle groups as described by the MSK neurology article. Have they assesses your lumbar spine for any possible issues?
https://www.caringmedical.com/prolotherapy-news/ischial-tuberosity-pain-ischiofemoral-impingement/
https://iaom-us.com/the-differential-diagnosis-and-conservative-treatment-of-a-distance-runner-with-hamstring-syndrome-a-case-study/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3812833/
https://mskneurology.com/identify-treat-lumbar-plexus-compression-syndrome-lpcs/