No data on retrieving user data

I am using the REST API to get the supporters of a community I’m part of.
The owner of the Patreon account supplies his own values for this, so it’s not something there, I’ve verified they are correct.

When I request the following URL ({CampaignID}/members?include=currently_entitled_tiers&fields[member]=full_name&fields[tier]=title), it will often return blank in the portion of the request. I know this works on some users, but not others, and will cause a crash if it does not exist, as we need to get the id of the tier they are subscribed to.
Is there a reason this is blank at time?