We apologize. Please check the following.
First, make sure the Apple Account signed in on your device is the one you used when you created the backup.
Then restart the device and check again. iCloud sometimes has temporary issues, and restarting the device often makes the backup appear.
If that does not help, open the Settings app, tap your name at the top, tap iCloud, and turn off iCloud Drive. Then turn it back on, wait five minutes, reopen the app, and check the iCloud backup screen. iCloud Drive occasionally has issues, and this resolves them.
We apologize for the inconvenience. If it still does not work, please contact us from the Contact Us button in the upper right and describe the situation in detail. Thank you.