This relates to the IOS remote no longer working properly with PHT & OpenPHT. See details in these threads:
https://forums.plex.tv/discussion/243726/plex-app-4-4-1-does-not-work-as-remote-any-more#latest
https://forums.plex.tv/discussion/244018/using-plex-ios-as-remote-for-pht#latest
An IOS developer is pointing to PHT as the problem, not the ios app, though downgrading to IOS app 4.4 fixed the issue for me.
Are there any plans to incorporate this fix into OpenPHT?