Exact same issue with HW-K450 - tried troubleshooting 3 times now with Samsung support, 1 chat, 2 telephone sessions (almost 40 minsutes each). Finally got it to work. Once. Went right back to same behavior:
1. TV turns on, Sounbar turns on
2. TV off, soundbar off.
3. Approximately 10-20 seconds, soundbar comes on, does not find TVCONNECT, shuts off.
4. Turn on TV, soundbar soes not turn on.
5. Turn soundbar on with remote, immediately connects to TV via TVCONNECT.
Reset everything possible except for TV.
I am going to try and escalate this in support - TV and soundbar are 2 years, 3 months old.
Also, one of the replies refers to the latest firmware updates - I am going to see if I can find out when my last update was and if that date correlates to the start of the problem.
Wanted to update in hopes that a Samsung person will see it and help fix the issue.
I lost internet connection tonight, ISP is doing maintenance. Because of that, I turned on my TV to watch some dvds since I don't have cable.
My speaker system turned on by itself as it should. I've turned the system off and on with the TV remote multiple times to verify it's working properly, TV remote turns TV on and the speaker turns on. I turn the TV off with TV remote and the speaker turns off with the TV.
So something that has to do with the ethernet connection (I don't have the wireless connection enabled as it made my router buzz), or the internet connection itself causes the TV to have this issue with the speaker not turning on with the TV.
Once my internet comes back online I'll verify it's not working. Then I'll test if it's only with an ethernet connection by switching over to wifi and unplugging the ethernet cable and update my findings on this post.
Update: once I got internet back the speaker stopped turning on with TV, and is back to turning itself on 5 seconds after turning TV off.
Also tried unplugging ethernet and trying wifi, same issue. So I have to conclude it's an issue only when the TV is connected to the internet. Or possibly the YouTube app as I only use that a lot for media consumption.
I have good news, we now have a fix for the Soundbar not turning on by the TV via Bluetooth.
Here's the Fix:
This version will be available on the support page for your model. Just pull up the full model code on samsung.com and scroll down and click on "See All Support" to get to the downloads section.