I have a TU7000 50" that had been working great for the last couple of weeks... Then the remote stopped being able to control my cable box (Spectrum Motorola/Arris dcx3600m).
Cable box is directly connected to TV via HDMI 1. Video/audio playback is fine, just can't control with the Samsung remote anymore. I tried removing the stb from the TV and seeing back up, but gets stuck at the channel up/down part (doesn't respond) even after inputting the model number directly.
I would contact Spectrum to verify that the cable box is updated on their side. If it is, I would suggest repairing the remote to the cable box.
You'll likely need to place the cable box closer to the TV so that the cable box can receive IR commands that are being sent from the TV. From there, you can go through the setup steps again and check the channel up/down test.
I have the same problem. Started about 2 weeks ago. Spectrum says it's a Samsung problem, Samsung says it's a Spectrum problem. My Spectrum box is a Motorola DCH 3416. Nothing changed with the TV (no software update, etc). My guess is that Spectrum updated firmware on the cable box and caused the problem. Getting newer model Spectrum box tomorrow. Hope it fixes the problem.
The same thing has happened to me as well. It happened all of a sudden on Friday. We just got the tv TU7000 (55") in the begining of July, and it was working fine in the weeks prior connected the an Arris Spectrum210A cable box. It's is crazy because it was working just fine. No problems at all, but since Friday it's been like the TV knows that it is connected to a Spectrum box, and the Spectrum box knows it's connected to a Samsung tv; but neither remote will control the other device. I have reset the cable box and have spoken to Spectrum tech support to trouble shoot. I've also did a factory reset on the tv but still can not get the tv to recognize the Spectrum box. I even entered the Spectrum model number manually, and I have spoken to Samsung tech support. Samsung is sending a new remote, but that doesn't seem to be the problem. Was there an update that happened to may have caused this?