I believe the reason why the initial solution I posted didn't work is because that entire fundamental hidden row isn't being generated correctly, and because all subsequent rows are generated from it, it affects their control visibility as well.
It's good to see that you found a workaround for your problem.
I'd be curious to know if this issue is persistent across your entire installation or just the particular form you're working on. The only way I could think to test it would be to make a Test List, start a new Classic Form, add a Repeating Section and a dummy Single Line Text, and just see what it looks like in the Preview. if it works correctly, then perhaps this is something limited to the troublesome form in question, however if it persists and is displaying incorrectly, perhaps it's something that could be corrected with a Nintex update or by taking it to Nintex directly (with a trouble ticket).
No matter, at least it's working now!
good day, can you post the final solution, cause mine is doing the same thing and it's not visible unless i change the «hidden» to visible in the dev tools.