Is this something easy to reproduce?
Yes it is. But you need to have xform patient registration form instead of default patient registration. Then when it is working add new patient identifier type on administration page and refresh it on xform design. Then test it if it captures all the data on textboxes.
I could have reproduced it here Login but there is no xform module and I can’t add it.
I have figure out the problem. Apparently when I refresh the form on the design view it changes the data type on textboxes from “text” to “single select”. I don’t know why it did that but after changing the data type and saving the form it is working.