It's around this time of year that schools in Scotland and NI break up early for the summer holidays.
In the past Scotland and NI have shown Ceefax on BBC TWO at around 6am and then joined the CBBC Digital channel (who would show more relevant programmes than CBBC on TWO as schools in England and Wales don't break up for another few weeks). This might just be a scheduling mistake on the EPG information (like when BBC News 24 appears in the listings but what's being shown is actually Pages from Ceefax).
If this is an error, it's a big one. It has knocked out three hours' worth of BBC Two programming from the EPG.
It's just suspicious that it has occurred at end of school term in N. Ireland. In previous years, BBC NI have filled part of this slot with a combination of Ceefax and the CBBC Channel.