Sometimes with equipment changes there are "race conditions". I don't think BA have much overall control over when processes start eg emailing changes

Eg last week I happened to open the android app and it said flight cancelled. I logged on to the Web app straight away to choose a flight but in the intervening two minutes the flight seemed restored. Phoned up the GGL line and was assured it was OK. Normally I look up the flight and aircraft on flightradar 24 and spot changes, but not this time. Similar event in Dublin in April