On a British keyboard, the following special characters don't work in the Save File Name and Trade Route name fields since GU13:
SHIFT+1 !
SHIFT + 2 "
SHIFT + 4 $
SHIFT + 5 %
SHIFT + 7 &
SHIFT + 8 *
SHIFT + 9 (
SHIFT + 0 )
SHIFT + ' @
SHIFT + , <
SHIFT + . >
SHIFT + / ?
Files have been verified
EDIT. =sign doesn't work either