I think I found some bug with using modules inputs inside a form container.
As a background:
I'm working on an Internationalization solution and wanted to create a module that would allow me to switch between languages and fill the translation for a specific language.
For that, I created a custom module that uses a tabs container to switch between input fields for specific languages with inputs to specify label and field key prefixes.
The module seems to be working as expected, but when I place it inside of the form container it doesn't evaluate inputs at initial load but when I do some changes to those inputs I get the expected effect. So there appears to be an issue only with the initial mount of the module.