This is a strange and known bug in FDM ( All versions from 8 to 11) , if you load any map with having & in any source member name it just corrupts FDM location ... Root cause of this issue is all FDM maps are stored in RDBMS and for any RDBMS & or @ are special characters so, it creates problems !!!... This is very irritating thing especially when you have given access to business users to load maps ..
1) Open the FDM Workbench Client and login to the application
2) Choose Tools/Table Editor
3) From the drop down list select the tDataMap table
4) In the "Find" box enter the location id for the location where the
mapping template was loaded. Scroll down to the entries in the table with
the DimName 'Account'. In the SrcKey field you will need to locate any
entries that contain reserved database characters (&,@, etc.). You can
delete these rows by highlighting them and clicking the X icon.
5) Click the Diskette Icon to save the changes.