Given that you have a tracker with a required selectbox with the following values: [A, B, C]
And an existing artifact has the field selected to A
When in field usage you change the value A to "hidden"
Then you cannot update anymore the artifact unless you edit the field to choose B or C.

You should be able to update the artifact without having to change the value of the field.

Analysis:
The form is not submitted because there is a required input that is hidden. Firefox silently ignore the click on the submit button, whereas Chrome raise an error about non reachable input. A possible solution is to reuse (and preselect) a value that is hidden if it is used by the current artifact. Other suggestions welcomed.