That is a problem if that target feature doesn't work. The only thing I can suggest is:
1) Make a copy of the project's directory (that is, the directory enclosing the project file, its source files and all of the supporting files/sub-directories.
2) In the duplicate directory, delete the _Data directory. That is, if your project is named junk, with junk.mcp, delete the folder junk_Data.
3) Now launch the IDE. Issue the following commands:
Project | Remove Object Code...
Project | Re-search for File
Project | Reset Project Entry Paths
This, along with deletng the _Data folder, are as close as you can get to a complete lobotomy of the project without losing all of your settings.
4) See if the target column works now.
Since you're working with a copy, if that doesn't work, you can fall back on your original.
The only other course of action is that you start with a new project, add your files, and modify your settings. If it is a corrupted project file, that will clear the problem. Yeah, right, it's a pain in the posterior doing that all over, but it can't be any worse than writing build scripts.