We have two Humax 9200T, one in the lounge and the other in the bedroom.
As far as I know they work off seperate aerial feeds from the same external aerial (i.e. the split is not from a junction box inside the house)

Today we have had two programmes recording at the same time on the bedroom Humax and nothing being recorded on the lounge Humax...
...but the available channels to watch on the lounge Humax are limited as if the two recordings were taking place on this machine!

Is this really possible?

Can't really imagine anyway this could happen. I have a 9200 and an 8000 connected to the same aerial and they have no effect on each other.
Did the available channels on the lounge box return when the recording upstairs stopped? Can you repeat the effect and does the same happen in reverse i.e record downstairs and lose channels upstairs? Does a power off on the lounge box while recording upstairs returm the channels? Wonder if its a form of the TIR bug?
Let us know what you find out. Its very intriguing?

Are you sure you have two distinct aerial feeds, and that your bedroom isn't a loop through from the lounge (or vice versa).

We have the situation where the main aerial feed goes into the Hummy, and then feeds onwards to other sockets in the house via a distribution amplifier so we can watch the same programmes on other room tellys. I could imagine this causing problems with a second Hummy connected.

The only other interaction I can think of (maybe) is if you have an aerial amplifier powered by one or both Hummys.

You must have done something to your aerial system when you connected you bedroom Humax.

Move it to the lounge and daisy chain the aerial from Hummy1 to Hummy2 to TV and check that will record OK - BUT you ought to check that you have set a different RF channel out - I think the default is 36 so you don't want them both on the same channel.

Change it to something in the 20's - and check that it doesn't clash with any other stuff - or local transmitters. You'll need to tune your TV to get that channel too - unless you use a SCART.

Ask for help if you need it - we are here to help.

You'll need to cover the remote eye on the Hummy you are not using - otherwise you'll be affecting them both.

We have both our Hummies in the same room and use a piece of black plastic to move to to one a want to hide - like an eyepatch!