11.3 (15E5178f) will not show up for iPhone X

I’ve tried uninstalling all my prolfiles, hard restart of iPhone X, talking gently to my iPhone telling it how pretty it is - all the usual tricks, but no matter what I do I can not get 11.3 (15E5178f) to show up in the software update window. Instead it just keeps saying “11.3 your is up to date”. Yet in the ABOUT screen it clearly says version 11.3 (15E5167f) is the version on the device. Anyone else having this “update” issue with iPhone X? It installed perfectly on iPad mini 4, iPad Pro 10.5” (newest model) and iPad Pro 2 - no problems on any of those at all, but neither of our two different iPhone X devices show 11.3 (15E5178f) as an option in software upgrade window.