CSV files will throw errors on Cloudflare pages if they have non-ASCII characters.

edit - just found a better version. Use this instead of the last one.

grep --color='auto' -P -n "[^\x00-\x7F]" _data/csv/*.csv

To check files run the following command:

grep --color='auto' -P -n "[\x80-\xFF]" _data/csv/*.csv

That will identify any files with non-ASCII characters.