The obj files for 'a' and 'A' have names a.obj and A.obj. On Windows, these are considered the same filename (filenames aren't case-sensitive), giving trouble.
Alternative: name the obj-files /resources/ascii/00.obj where 00 is replaced by the hexadecimal code for the ascii-equivalent of the character. For example, the uppercase 'A' would be at /resources/ascii/41.obj.
The obj files for 'a' and 'A' have names a.obj and A.obj. On Windows, these are considered the same filename (filenames aren't case-sensitive), giving trouble.
Alternative: name the obj-files /resources/ascii/00.obj where 00 is replaced by the hexadecimal code for the ascii-equivalent of the character. For example, the uppercase 'A' would be at /resources/ascii/41.obj.