Problems with luaotfload and certain font shapes

Problems with luaotfload and certain font shapes

While playing around with lualatexon TL 13 I encountered a strange problem. Certain font shapes would produce an error without any visible reason. The following example is with Stempel Garamond LT Std from Adobe's Font Folio 11, but I've encountered this with other fonts as well.
\documentclass[]{scrbook}

\usepackage{fontspec}
\setmainfont[Ligatures=TeX,ItalicFont={Stempel Garamond LT Std Italic},BoldFont={Stempel Garamond LT Std Bold},BoldItalicFont={Stempel Garamond LT Std Bold Italic}]{Stempel Garamond LT Std Roman}
\begin{document}

Regular \textbf{bold}  \emph{italics \textbf{bold italics}} 

\end{document}
This leads to the following error message:
LaTeX Font Info:    Font shape `EU2/StempelGaramondLTStdRoman(0)/m/sl' in size <10.95> not available
(Font)              Font shape `EU2/StempelGaramondLTStdRoman(0)/m/it' tried instead on input line 10.
luaotfload | load: auto-selecting default features for script: latn
luaotfload | load: no defaults for script “latn”, falling back to “dflt”
luaotfload | load: invalid request “/Users/simi/FontExplorerX/S/Stempel” of type anon
luaotfload | load: use square bracket syntax or consult the documentation.
luaotfload | load: path lookup of “/Users/simi/FontExplorerX/S/Stempel” unsuccessful, falling back to file: ! Font \EU2/StempelGaramondLTStdRoman(0)/m/it/10.95=/Users/simi/FontExplorerX/S/
Stempel not loadable: metric data not found or bad.
<to be read again>
G
The really strange thing is that it produces the following output:
As you can see, luaotfload actually does find the correct font shape.