Since you've already checked attachments and conversations and confirmed they aren't the source of your storage issue, the mysterious 5.02GB of "Documents & Data" in your iCloud Messages storage is likely due to cached data, orphaned files, or synchronization glitches. Sometimes, iCloud accumulates invisible cached files or corrupted data that don’t get cleared by standard cleanup methods, resulting in this discrepancy.
One effective approach to resolving this is temporarily disabling and then re-enabling Messages in iCloud. To do this, open Settings on your iPhone, tap your name at the top, select iCloud, and then toggle Messages off. When prompted, choose "Disable and Download Messages," ensuring your existing conversations remain on your phone. After disabling, restart your phone by going to Settings → General → Shut Down, then power it back on.
Once your device restarts, turn Messages in iCloud back on, allowing it to resynchronize fully. This often clears phantom data and corrects storage inaccuracies.
If toggling Messages off and back on doesn't resolve the issue, signing out and back into your iCloud account can help remove lingering orphaned data. Navigate to Settings, select your name at the top, scroll down, and tap "Sign Out." Provide your Apple ID password as requested. After signing out, restart your iPhone, then sign back into your iCloud account and re-enable Messages synchronization. This method can clear deeper synchronization glitches causing inaccurate storage reports.
Should these steps not fully resolve the issue, performing a backup and restore through a computer can help clear persistent cached files and corrupted data. Create an encrypted backup using Finder on a Mac or iTunes on Windows. After backing up, restore your phone from this backup, which often eliminates hidden storage anomalies.
Additionally, it's helpful to check your actual iCloud storage breakdown online by logging into iCloud.com. After signing in, visit Account Settings and then click Storage → Messages. If the online storage calculation differs significantly from what your phone displays, it further indicates synchronization errors. Often, allowing several hours or up to a day after performing the above steps gives Apple’s servers sufficient time to recalculate and accurately reflect your storage usage.
Typically, the first solution—temporarily disabling and re-enabling Messages in iCloud—is the safest and most effective starting point. The other methods can be pursued if needed. Remember, none of these approaches should permanently delete your messages if you select "Disable and Download Messages," but it's always wise to maintain a current backup before making changes. Avoid third-party apps claiming to clear iCloud storage, as they might compromise data security.
