Dan,
Can you copy in the exact CACHEFINANCE() syntax you used so I can try in my test sheet:

https://docs.google.com/spreadsheets/d/1zk7GIJ7ys4hBhiZwrLemqIGf-lH7eiLcJWKw6IkdAY4/edit?usp=sharing

The test sheet is probably not exactly what I have posted in Github since I don't put stuff not fully tested. (so github should be stable while I test on this sheet). You can also try on that sheet as well. Hopefully this link allows update access.

Chris.