I do do not have XL TV my package is M+ but this covers Sky 1 and I watched episodes 1 and 2 on demand. I went down a similar path to the one you suggested Home/TV/On Demand for M+/By Channel/Sky On Demand/Sky 1/All A-Z/ but it shows no shows under You, Me and the Apocalypse.
I have several episodes available under Zoo Arrow and others just not You, Me and the apocalypse.
It it has been like this for several weeks now. I keep trying from Explore this show/Episodes/Get from on demand which is where I see error 6175 saying try again in a few minutes.
Thank you for coming in and posting back to us here.
I'm sorry that this is still ongoing, I've had a look here and from the TiVo side, things are looking healthy with no signs of problems on the signal side.
That code may signify that the services may have been a little busy during the time you tried to view this. Since our conversation last, have you been able to view the show or any other shows from the On Demand?
Keep in touch and if there's anything I can do please let me know.
I have still not been able to access this on demand show. If I select the HD version I get no error but would have to subscribe which I don't want to pay for as I should be able to access the SD version. This appears to be a problem for the M+ subscription as if I go through home>on demand>tv> for the M+ it lists the show but when you go in it only has the second episode.