Investigate why tAppendices and tChapter11 don't run

[remo-pillat]

They show as "Incomplete" in the latest test run logs with no further explanation, e.g. see this raw log.

Failure Summary:
2025-03-20T03:34:53.6392097Z
2025-03-20T03:34:53.6392212Z Name Failed Incomplete Reason(s)
2025-03-20T03:34:53.6392493Z =======================================================
2025-03-20T03:34:53.6392782Z tAppendices/runMLXFile X X Errored.
2025-03-20T03:34:53.6393097Z -------------------------------------------------------
2025-03-20T03:34:53.6393401Z tChapter11/runMLXFile X X Errored.
2025-03-20T03:34:53.6393594Z