It would not surprised me that particular movie, at that precise spot is somehow corrupted and Netflix needs to run a repair/restore or something, move it to another HD blah-blah. Just like what can happen if you have archived movies on your own HD. Tech support at most companies, am afraid to disclose to you, being one myself in another life, are mostly "phone answerers" and all they can do is follow a "procedure sheet" given by their supervisors and have you walk through it. The engineers who knows what's exactly going on and have direct access to resolve things don't answer your calls, they let you suffer through the bureaucracy.
Am sorry if you are binge watching or something and are stopped cold on this particular episode, but am confident Netflix's internal "repair" mechanism will take care of it in a couple of days, just find something else to watch in the meantime.
If this happens to all tittles, I suggest follow TCL manual and reset TV to factory, and DO NOT perform firmware update, suspecting latest update broke things.
Another thing to do with streaming services is, attempt to reset App to "virgin." I don't remember if TCL/Roku has something like this, but on my Sony is says something like reset App information or something, that has the effect or making the App "forget" your account info (suspect corrupted) and starts the App anew and asks you for account info as if u just opening the App for the first time.