I was just talking to someone who came back from working in Shanghai and that’s not what she told me but it’s very possible she misunderstood my question.
ROC and PROC don't recognize each others' passports, since both states hold the official position that the other state does not exist (and that travelling between the mainland and Taiwan does not, therefore, count as "international travel").
https://en.wikipedia.org/wiki/Mainland_Travel_Permit_for_Tai...