On a piece of navigation software, GLM hallucinated astro tables instead of using a library. I wondered why my sun sight was 1000NM off, and then it confessed.
On the current offshore passage I got to within 7NM of GNSS position, so the fixed version works. 7NM might sound a lot, but from the deck of a small boat in big seas it isn't bad, and totally enough for making landfall.