I don't think you are using :colnames correctly. If you check the info manual, it starts by saying:
"The ‘colnames’ header argument accepts ‘yes’, ‘no’, or ‘nil’ values." (org) Environment of a Code Block The assumption is that the input table has column names and you want to handle them in a particular way. -- : Eric S Fraga, with org release_9.7.11 in Emacs 31.0.50
