According to the Freeview website, there are no scheduled engineering works at the Emley Moor transmitter. Neither are there are any emergency works, according to UKFree.tv (which is usually a reliable source of information). That strongly suggests that the problem is 'at your end'.
Freeview channels are transmitted in 'bundles', called multiplexes, with each multiplex being on a different frequency. All of your missing channels are bundled into the 'COM 4' multiplex, meaning that they're all using the same frequency. I strongly suspect that your aerial isn't up to the job of receiving that particular frequency when reception conditions are poor (as they're likely to be at the moment, due to a high solar flux index).
In an ideal world, you'd have a different aerial on your roof for each different multiplex, meaning that you'd need to have seven aerials up there (because the signals from Emley Moor are bundled into 7 multiplexes). That's clearly not practical, so we all use aerials that (by the laws of physics) will 'resonate' better on some frequencies than on others. Your aerial isn't much good at receiving signals on 570 MHz (which is the lowest of the seven frequencies in use and is the one used by COM 4). It can 'pull in' signals on that frequency when conditions are good but when, say, there's a lot of solar activity (as there is now), it simply can't cope.
When the switchover from analogue TV to digital TV was due to happen, it was predicted that around of third of homes would need a new TV aerial (because digital TV uses different frequencies to analogue TV). It turned out that far fewer homes actually did but it's still not very surprising when people find certain channels (almost always on a common multiplex) dropping out.
The good news though is that you probably don't need to fork out a lot of money to get a new aerial fitted. As you're getting adequate signals most of the time, simply installing one of these should solve the problem for you:
https://www.argos.co.uk/product/3036040
(You'll need one of these to go with it
https://www.screwfix.com/p/philex-coaxial-cable-1m/41720 and you'll probably need to retune after installing it).