Holding table under the record can be too wide if filters are activated : item type, holding library, home library and status are now filtered by dropdown lists. If the labels of some libraries, types or status are long, their respective columns are enlarged. As a result, the holding table overflows the page, and the action button at the right (Edit) is not visible unless the librarian scrolls the entire page to the right. I have no idea of the best way to fix that, but this is an UX and accessibility issue.
Note that even if you don't activate filters the holding table can be too wide but the problem is more likely to occur if the filters are enabled.
I think it's a duplicate of bug 35908.