Did you book direct with TAP or via a travel agent? It's generally the one you booked with that sends you notificattions (e.g. it was expedia that notified me that the time of an AA flight that had changed not AA as I had booked using expedia)
I have also see the case where someone - as you did - checked MMB and found a change but the airline was yet to send the notification. This is more common where the cancellation is a good few months away and they will send emails out to customers with closer flights first to prevent the call centre being inundated..
Yes the retiming at the moment looks stupid but when a flight changes the IT systems will just book you on the closest other flight and then any other needed changes filter through the system in the next few hours and dates
As advised best to look to other routings to get you back to DUB and then contact TAP. Most other reasonable airlines would rebook you onto alliance partners but not all will.