To avoid this issue in the future:
This is the most reliable way.
Sometimes the main app glitches. Try Instagram Lite (Android) or log in on a friend’s phone to see if the blocked list loads correctly.
and tap the three horizontal lines (☰) in the top right. Select Settings and privacy .
If a user their account, they essentially disappear from the platform. You cannot unblock them, and you cannot view them until they log back in and reactivate their profile. In this case, you simply have to wait until they return to the app.
How to Block and Unblock Someone on Instagram - Security.org
Instagram users often encounter a frustrating paradox: they try to unblock someone they previously blocked, but the platform responds with "User not found." This message typically appears on the unblock confirmation screen or when searching for the user’s profile. Understanding why this happens is the first step to resolving it.
