Gapless Playback (iTunes 12.7.2.58 + iPhone 6 iOS 11.2)

How is gapless playback determined for songs since the feature was removed to manually apply 'gapless playback' in a previous version of iTunes? Because with fully up-to-date iTunes and iOS installed all my albums that previously played gapless now do not play without a 'break' in between songs.

I've tried converting to different formats, re-syncing to my device, and nothing seems to make a difference