I tested iOS 11.3 beta 4 / beta 5 Apple Pay Suica Express Transit performance on iPhone X in the hopes that Apple fixed the error flicker issue. So far no luck. See for yourself.
UPDATE 1
iOS 11.3 does not fix the iPhone X Suica problem.
UPDATE 2
iPhone X has a NFC hardware problem, for more information see:
iPhone X Suica Problem Q&A Exchange Guide (English Version)
iPhone X Suica問題Q&A交換ガイド（日本語版）