Hello William,
Thank you for sharing the dataset and sample code. However, it works as expected on my test system:
chunk.detectMarkers(target_type=Metashape.CircularTarget12bit, tolerance=100)
2021-05-04 18:35:16 DetectMarkers: marker type = Circular 12 bit, tolerance = 100
2021-05-04 18:35:16 Detecting markers...
2021-05-04 18:35:17 0200ccd6-7809-4cb4-869c-55ead3f74e41__IMG_0089_8: 0 targets
2021-05-04 18:35:17 2a50712c-8ebf-4e62-8b49-b7fa7920a993__IMG_0089_7: 0 targets
2021-05-04 18:35:17 26a8624f-01f8-4a89-9a67-e26863640c0f__IMG_0089_10: 0 targets
2021-05-04 18:35:17 da161590-ec3a-4665-9df5-1a60ce6c1823__IMG_0089_9: 0 targets
2021-05-04 18:35:17 355177db-1a7f-4fea-a8e3-499f3a7a963a__IMG_0089_6: 0 targets
2021-05-04 18:35:17 Finished processing in 0.394 sec (exit code 1)
If there are multiple RAM modules installed on the system, where the problem is observed, you can also try to leave only one module at a time and check, if the issue is observed on the certain one module. In case it is reproducible on any module, you may need to lower the RAM frequency.