Maybe wrong file permissions?
In my installation they look like this:
senaite :: ~ » ll /home/senaite/senaitelims/src/senaite.core/bika/lims/browser/worksheet/templates/print/
total 44K
drwxrwxr-x 2 senaite senaite 4.0K Mar 18 2019 .
drwxrwxr-x 3 senaite senaite 4.0K Mar 18 2019 …
-rw-rw-r-- 1 senaite senaite 2.0K Jul 17 2018 ar_by_column.css
-rw-rw-r-- 1 senaite senaite 5.0K Jul 17 2018 ar_by_column.pt
-rw-rw-r-- 1 senaite senaite 1.9K Jul 17 2018 ar_by_row.css
-rw-rw-r-- 1 senaite senaite 4.1K Jul 17 2018 ar_by_row.pt
-rw-rw-r-- 1 senaite senaite 8.1K Mar 18 2019 README.rst