It could be the Humax or it could be 1 of many other causes. You’ll need to play at being a detective.
Have you a freeview TV or other STB at you could check that your aerial and its cabling and possible mast-head amplifier are OK?
If not then perhaps you have a local friend you can try out your Humax using their aerial.
Also when do the recordings go up to? If they stopped as soon as you went away that that suggest you have a mast-head amplifier that you inadvertently turned off its power supply.