It will hang, waiting for a connection with an overlayed message saying "connecting." I wonder if your experience is the same thing. When you go to a channel, it might stay black waiting for the program info (which apparently is being retrieved from the internet, not the OTA broadcasted guide).
The only solution I've seen is to do a factory reset, and tell the setup you don't have a network connection. It will install whatever version of software the tv came with. You can then use that as an antenna tv (without any streaming ability, because you'd never connect the tv to the internet.). If you need streaming, you could buy an external streaming device. I'm not familiar with them at all (Amazon fire? Apple tv? Roku has some. But, if you're not feeling the Roku love, it seems out of place to mention them.).
If you dig Roku TV's streaming, you could buy an external digital tv tuner with HDMI connection. Watch antenna tv using an external box.
One downside to that is: Rokus updates are untested. It would probably be better to use it as a factory-reset & disconnected antenna tv (so it's never molested again by an update).
However: Roku's antenna interface was never that great. The external boxes give you numeric remote keypad, favorites, the ability to add channels without a destructive rescan. Also the ability to schedule recording of a show (or, timeshift a show while watching it). Could be much better in some ways than devoting the Roku TV to antenna watching.
Last week I bought three tuners (Mediasonic HW-150, TV View AT-300 & iView 3500). I used to *love* my old DTV "converter" boxes. They were simple, easy to use. I'm hoping one of these will be as good. (I need to make time to look at them). One forum member bought the HW-130, which is supposed to be the same as the 150, but scaled down. They didn't like it. So, I could be wrong about these. I need to make time to look at them the next day or two.
The point I'm making: it's quite likely nothing is going to change. If you look back at problems, we could be talking about this one a year from now. It could be deliberate, not a bug. It's likely it won't change (if history is any guide). So, those are your options. 1) Make it a non-streaming antenna-tv (using whatever old version of software it came loaded with). Or, 2) use it as a streaming tv, and add an external tuner (however bad those devices are. I don't know yet. But, one person wasn't happy with it.).
You can find youtube videos demo'ing those boxes. You can get an idea what it's like. What's not clear enough to me yet (won't know till I set down with the three I have) is if it's a reasonably intuitive/helpful interface. If it feels nice to use. (My old DTV converter boxes were. A Zenith & Digital Stream. They weren't rough, or too tedious. They didn't get in the way. I could do what I wanted to do with favorites, and changing channels, rescanning as an update, not destroying/replacing what I already have. I'd love to have that again. Obvously, it's looking better to keep things separate (not all your eggs in one basket). I like the idea of a separate box in those terms.
"People are often amazed at how much we’ve done with the number of engineers we’ve got." (Roku CEO Anthony Wood, Austin Statesman, Oct 4, 2019). "Amazed" is one way of putting it.