First guess is it's a resolution issue. The display isn't syncing with whatever resolution the other sources are sending. I presume they are lower quality than the sat receiver so bandwidth shouldn't be the cause.
As a possible other cause.... I use a Yamaha receiver (same deal with two different models) with dual HDMI outputs (tried both). One display is a LCD (PC) monitor that doesn't have HDMI. So I use DVI instead and it's a pain in the neck. Every time I change resolution the display goes blank (I even tried the service menu tweak MON.CHK) and I have to turn it off and back on to get the image back. Might be having similar syncing issues with your extender. Pioneer didn't have the issue and Marantz and Denon to some degree... if I remember correctly.
Might be a completely different case but when they closed out the RX-A820 (over several weeks) they dropped a price a few times. Luckily, for me my credit card company refunded the difference (price protection plan). I might punt the RX-A820 into another room if the RX-A1020 drops any further. I'm sure they sound the same but that extra 10 lbs helps it from falling off the shelf.