Files with non-ASCII characters in the filename are not scanned.
I think this is caused by line 277 in svs_sync_scan():
QFileInfo fileInfo(QString(path) + "/" + QString(file));
From the QString documentation:
"QString::QString ( const char * str )
Constructs a string initialized with the ASCII string str. The given const char pointer is converted to Unicode using the fromAscii() function."
To reproduce, create a directory containing a non-ASCII character such as Æ, and try to copy a EICAR test file to or from the directory. I tested on a system with UTF-8 encoding.