Solution
This problem can occur when an XControl or a .lvlib file containing an XControl file is placed in a project. The XControl will occupy the library resources as soon as it is placed within the project. This causes the project libraries to become locked when a VI containing the XControl is open.
Because your libraries are locked within the project, you are unable to edit any of the files in it. To correct this, either close the VI containing the XControl or unlock the library for editing by right-clicking on the XControl library and selecting
Unlock Library for Editing. You can then edit files within the library. However, this will cause the XControl and the VI to be unusable until you re-lock the library by right-clicking on the XControl library and selecting
Apply Changes to Instances. To find out more information about unlocking an XControl library, please see the LabVIEW help file
Editing XControls That Are in Use.