We have experienced this issue in the past, see
https://github.com/BartVandewoestyne/oaconvert/issues/45 The problem seemed to be that some of the OpenAir files were not UTF-8 character-encoded. Simply saving them as UTF-8 solved the problem. Are you experiencing this with the latest version of the files? As soon as I find some time, I will check this to see if this problem re-appeared with the latest files. If it does, I should be able to fix it easily.