Answering your questions:
Is there any depends_on logic that you may have overlooked?
Is there a custom script that may be setting it to hide unintentionally?
There is but doesn’t have any code that can hide the button
Are you opposed to injecting a custom script to ensure that it is not hidden when docstatus == 1?
I’ve tried to do this but without success
In order to isolate the problem, I’ve made a new custom DocType with only a button and nothing more, not depends_on nor a custom script that could be changing the behavior and It seems that the “hide behavior” is by default.
Thanks again for your help