Authenticator not always working?

For some reason, our authenticator is only working 50% of the time. It is really strange and I'm wondering if anyone has encountered this type of issue or could advise me. My Software team and Qualtrics support are unable to advise. Basically we are capturing a UserID field through our website. This is the same value as the externalreferenceID. For some reason though, it's only synching sometimes. I modified the survey flow so it synchs now, however our sample has declined 50% leaving me thinking it's now not letting folks answer questions.