That sounds like the Customer Information System, rather than the screens. "Disruption mode" means trains will be hidden from screens unless they are "known to be running" (i.e. not "delayed"). That's up to Greater Anglia to manage.
This mode is hardware-agnostic, I don't often see TOCs use the disruption mode feature any more as it just causes more confusion amongst passengers and staff (app vs station screen confusion).
These screens don't work in the same way as the Infotec ones and their disruption mode and the solution provided by the supplier is a full customer information system , replacing Javelin. The new system also has a text to speech functionality for audio announcements.
I've seen stations with both in and the Infotec ones have been correct whereas these new ones have had the problems that the other posters have explained. I believe these screens don't use the same raw feeds, since the old screens always used to be in line with other systems where I often find the new ones don't. When Ipswich had a mixture of both systems for a short while this was very noticeable.
I suspect that whereas the old system was using raw feeds, this new system may see the data coming in, tweaked or modified in some way and then going out to the screens. Certainly when procuring this system,
Greater Anglia stated that one of the major benefits was that they were not restricted to the raw data and they could customise it. They may well be taking all the data in, storing it somewhere, doing some post processing and then spitting it out differently rather than the more simple nature done previously. That would account for the lag these screens have as well.
The problem is that I've noticed when services are delayed, they stay on the new screens until they arrive, which is a problem as it may mean that services which are actually running don't show, because slots on the boards are already taken up. However sometimes at Cambridge they've re-ordered by expected times, which is also weird.
All these screens have shown is that Infotec's experience in the industry over a couple of decades or so is extremely valuable, since they have solutions for these kind of problems and have come across them before, that's what experience gets you.