@juancho
In my testing- once you left the page and returned, there were no more instances of the “disappearing” marked shipped. It stayed. It seems to only happen on the refresh– so it should not affect your vendor’s accounting . Let me know if this turns out to not be the case on your site.
Go ahead and ask here- yes, that is fine. I am glad to help how I can, and we can keep your questions in this thread since you are the original author of the thread / topic.