An unknown number of Twitter users are experiencing an issue that makes them unable to view their lists on iOS devices, a Twitter spokesperson told VentureBeat today.

“There is currently a bug affecting lists on Twitter for iOS, but people should still be able to see their lists on,” a Twitter spokesperson told VentureBeat in an email. “We are working on a fix and expect this issue to be resolved shortly.”

VentureBeat has asked Twitter for additional details about the number of affected users, the cause of the disturbance, and when the issue first began. We will update this story with more information if we hear back.

On desktop, iOS, or Android, tap your profile icon and Lists is the second category you’ll see, right below your profile.

Each Twitter user has the power to create, add to, and curate lists of Twitter accounts they want to follow separately from their Twitter Home feed of accounts they follow. As noted by The Register, lists are often used by journalists, marketers, activists, and others interested in keeping track of tweets from certain users. The Register reports that users have experienced the problem for several days and that some were concerned that lists created and curated over time were gone forever.

In other Twitter news, Night Mode, the ability to view Twitter with a deep blue background akin to the night sky, launched today for desktop users. Just click on your profile icon and the option should appear at the bottom of the pull-down menu.