I also have this exact issue, and I am also on Rowridge, though I didn’t think of the transmitter being implicated.
I can tell you the ‘fix’ - Settings/General/Programmes/Programme Tuning and Settings/Programme List Update - set this to Off.
(The exact journey from Settings to Programmes varies across my four LG TVs).
After that, if the programme list really changes, you will get ‘Programme Map Changed - do you want to retune Yes/No?’ and you can do this when it is convenient for you.
As to the problem, it is the TV waking up once a night to check the Programme List, finding no broadcast channels, or thinking that it has, and in a massive failure of common sense, deleting all the ‘missing’ channels from your EPG, leaving only the few IP ‘channels’ that are always there, as per your first picture (even though I can’t see either image, I’m pretty sure what they look like).
And then not waking up later on to check again, and maybe put the channels back.
LG should fix the check so that if it finds no channels at all, it leaves things alone, or reschedules the check for an hour later, or some such.
It would be interesting if anybody else reports the same issue here, and from what transmitter.
I might ask Freeview what they think, as well.