@JosephWright in
tex.stackexchange.com/questions/141520/… egreg points out that there is a missing
{}
in storebox.sty but if you do
\AtBeginDocument{{}}
as a "temporary" fix the
{}
magically drops in to the right place, but with the new hook code it has started failing, but that temporary fix was in 2013, it might be time to actually fix the package.