I know you're trying to help, but your answer is the same as all the other answers to this problem which didn't help. I know how to check my iPhone's storage as I had stated. I have read all the articles about managing storage. But I have 12 GB of free space on the phone out of 64 and it still says "iPhone Storage Full". There is obviously an error either in how IOS computes the available storage or how it determines when to set the indicator flag in Settings.
In case you need to know, I have 4.4 GB unused space out of 5 in iCloud. I wouldn't think this applies, but I haven't seen any documentation that says it doesn't.
Thanks for you attention!