iOS 10.3 Safari cookies won't delete

I've had the same issue with being unable to delete a number of "0 Bytes" cookies on my iPad for a while, but recently an eBay.co.uk cookie of 508KB size began to exhibit the same behaviour - at which point I "snapped", enough is enough! I found a solution, however it's a little long-winded and requires a Mac:

1. Connect the iOS device to a Mac and create a backup using iTunes
2. Open the backup using an explorer/editor tool such as iBackupBot (I was a little dubious about using this at first, but it was signed by a registered developer and did not require installation nor did it ask for a password input at any stage, so pretty safe)
3. Navigate to the folder "User App Files > com.apple.mobilesafari > Library > Webkit > Website Data"
4. Delete all files and folders in the enclosed IndexedDB folder - this is where the 508KB of eBay data seemed to be
5. Delete all files and folders in the enclosed WebSQL folder - where all the other "0 Bytes" cookies are stored. I was amazed there were even cookies in here which didn't show up in the Website Data view in Settings. Mine had a whole trove of cookies from argos.co.uk, ebay.co.uk, and uk.farnell.com amongst others.
6. Restore the backup to your iOS device using iTunes

This was sucessful for me on both my iPad Pro and iPhone SE - both on iOS 10.3.3. I can't confirm if it will work for iOS 11 devices, but from what I've read many people have found the cookie problem to be fixed in 11.1.2.