There seems to be an issue where a browser tab will close when selecting "New Item" from a bib record that was opened from the "Manage staged MARC records" page. There seems to be a similar issue reported in bug #24011. https://bugs.koha-community.org/bugzilla3/show_bug.cgi?id=24011 To reproduce: 1. Open a staged MARC record 2. Click to open one of the biblio records. 3. Click "New" then "New Item". 4. Watch the browser tab close. The library that is reporting this are using a workaround that consists of reopening the last closed tab which will then stay open on the "Add item" screen. This also seems familiar in this bug https://bugs.koha-community.org/bugzilla3/show_bug.cgi?id=23680 All these have been reported in 19.05.
*** This bug has been marked as a duplicate of bug 23680 ***