If you are experiencing Location properties not reading the correct property when working through external references, you may want to see if the problem is similar to one I recently experienced.
A project in my office was being done in ACA 2010, and was not using the Drawing Management (Project Browser/Project Navigator) feature. Space objects were placed in the main "model" file, and had the company standard Property Set attached which includes two Text-type Manual properties for the room name (for two separate lines, set up before attributes in the view block of a Multi-View Block tag could wrap text), a formula property to concatenate those two Manual properties, for use in Schedule Tables and a Manual room number property. The Property Set was an older version, which also has three "residual" properties from the out-of-the-box property set, a Project property for Level, an Integer-type Manual property for the room number "Increment" and a formula property to concatenate the Level and Increment properties. A separate Property Set was also attached to the Spaces to hold a project-specific Text-type Manual property to hold the "room code".
In order to allow additional staff to work simultaneously, the equipment for the project was placed in several different "equipment" files, which were then externally referenced into the main model file. The main model file was also externally referenced into the equipment files, so that the equipment could be located. The equipment had a Property Set that included three Location properties: one for the concatenated formula property for the room name, one for the room number and one for the room code.
There were a number of issues with the state of the files at the time I was consulted. Once I got the needed Property Sets attached, I found that the room code Location property read the information correctly, but the room name and room number properties were displaying *No Project* for a value. I double checked to make certain that the correct properties were being referenced, and that these did not make use of the Project property. All appeared to be set up correctly.
I finally discovered what the problem was (even if I do not understand why it was a problem) - the equipment drawings had our current version of the Property Set for room names and numbers, which no longer have the "residual" Project-based properties. For some reason, the fact that this was different from the version of the Property Set in the main model file caused ACA to become "confused" (no, that is not a technical term) and resulted in ACA grabbing the wrong property values from the main model. I discovered this when I added two more Location properties, referencing the two Manual properties that make up the room name. The Location property referencing the first line property also displayed *No Project*, but the Location property referencing the second line property was displaying the value of the first line property! At that point, I discovered that the Property Set in the equipment drawings was different from the one in the main model file. I did not want to take a chance on losing all of the values for the room names and numbers in the main model file, so I copied the version in that file to the equipment file, and, just like that, the Location properties started referencing the right properties.
So, if you are seeing a Location property in one file referencing the wrong property from a Space in an externally referenced file, one thing to check is whether the Property Set that has the Space property being referenced is identical in both files.
As part of my diagnostics, I opened the ACA 2010 files in both ACA 2011 and Release Candidate Beta 2012, and the problem occurred in those versions, also.