So if I understand correctly you can import files but just not those exported for this document?
First of all, if you look in the export folder - can you see a great deal of .xml files, basically one per object and some additionals? If you have 10 sheet in the document there should for example be 10 xml-files for these sheets (by defaults SH01,SH02 etc)
Secondly, do the objectsnames in this document follow standard/default naming (LB11, TX123, SH06 etc) or have they been renamed? If they have been renamed - if any contain special characters that that might explain it.
My suspicions are that either there are special characters in objectnames or that not all sheets and objects were exported as xml filel (as you mentioned some sheets are not shown for all)
I took a look at the files and it is indeed the filename "ENG Std%2E 3.xml" that causes the issue. In the QlikViewProject.xml (used by the scalability tools) the corresponding name is "Document\ENG Std. 3". So the actual xml file percent encodes the dot fin the filename but not in the QlikViewProject.xml.
Anyway, I replaced %2E with a dot ("ENG Std. 3.xml") and I can import the file so that should do the trick.
The easy solution for now if this occurs is to replace any "%XX" to the characters they represent, but it's possible that we do an update to the tools or documentation ragerding this sisue as well.