I have so far discovered two devices where /ipdevinfo shows "Function N/A", but "Edit IP device" (and database queries) shows that data is present. The only "special" character is hyphen, but other devices with hyphen in the Function string displays them correctly.
I have also tried to change the Function string, but still displays as N/A
How to debug?
It also seems like it is impossible to empty the Function field (both on these two devices and others I have tried.) If you delete what's written and clicks Save the text reappears.