This has probably been asked and answered already, but I can't find anything, so I'll ask (possibly) again if that's okay.

Got my Humax PVR just after Christmas and it's great, but the other week I thought I'd try putting it into Non-Freesat mode, so that it would simply list every possible channel. Only really did it to "play" to see what would happen.

Took a while, and found a silly amount of channels, but when it had finished it didn't seem to have any correct numbers for the channels. I opened up the EPG and it presented me with something like channels 50163 to 50169. I scrolled through a few pages in the 50000 range, saw nothing recognisable, and then went back into Freesat mode, deciding never to go into non-Freesat mode again.

Is this normal?

Do you have the latest firmware installed?

I had this too the 1st time I tried it but now I have re-done it and have an almosty complete list of named channels with only a couple named by number alone.

You should also be aware there's no EPG in non freesat mode so only instant recording is available. However, you can switch between Freesat and non Freesat mode at will using the set up option and the epg and scheduled recordings will still be in the Freesat EPG (you only lose any timers on a channel scan in non freesat mode - known bug).

The channel numbers in non freesat mode are not fixed the actual channels but are generated as you add the channels so the order affects the channel numbering. As you say there's hundreds of channels that are pure rubbish. Best plan is to find the channels you want and add each transponder separately so you only get the channels you want. One that is worth adding is Luxe HD (not so much for the content as it's excellent HD picture quality).
Make a note of any programme reservations as adding/deleting/moving channels in non freesat mode deletes these, once they are there you can watch/record without affecting freesat reservations Go into non freesat mode and delete all channels. Go into manual tune and this time change the transponder setting to 12643 H 27500 2/3 this will find Luxe HD (and two BBC SD regions) save these. You can delete the SD channels if you wish. Whils't there you might as well add BBC HD so you can record BBC HD in a non encrypted mode (scan 10847 V 22000 5/6).