I know this thread is old but I have the exact same issue, I have one of the 75 inch Samsung smart tv's (no 3D) that had the old type of smart hub. The one that showed up in the whole screen when you pressed the smart button. Unlike the newer 4K tv's that show the menu as a bar of icons on the bottom and you can still see what's going on on the tv.
Then a few months ago I did a firmware update and they changed from the old style smart hub to the new one, so now my smart hub is just like the new tv's, the problem is that now every time I turn on the tv I can't instantly hit the smart button to have the hub show up, I have to wait at least 30 seconds, or else I just get a message saying "smart hub is updating" when I press the button. After 30 seconds or so, if I press it, the hub shows up correctly now as the new version with the icons on the bottom.
Searching online for solutions has been pointless and telling Samsung has even been more pointless. I had a Samsung technician come to my house for another reason (tv had a faulty board and they exchanged it) and when I asked him about the issue of the smart hub and the update and all that he just looked at me as if I told him to broker a peace treaty between Israel and Palestine. In other words, he looked at me like "WTF?!?"
The only reason why I am replying to this thread is because I noticed there was a recent reply, so hopefully someone is still watching this.
If there was a way to downgrade to the last version of the firmware that still used the old style smart hub, this would make my life easier.
Sure, waiting 30 seconds before pressing the button isn't exactly a big deal but the whole point of a smart button is to use the integrated features of the TV as opposed to an external device like Roku, Apple TV, PS4, etc.
What is the point of having that smart hub button if I can actually turn on the tv, switch to the HDMI port where my Amazon Fire stick is connected and then run Netflix on the fire stick, all while the TV itself still isn't ready to launch its own smart hub because it's "updating"
Kinda silly, isn't it? I still love my TV and won't sell it for a while but thanks to that issue I abandoned all intentions of using Samsung apps, which I actually used a lot (weather, Netflix, Amazon video, etc.) and have been using the fire stick I had downstairs instead.
Please, someone give me a solution if you find one.