Problem with packed files


sometimes I have problems with packed files. On saving blender says ‘could not find file XYZ’.
Sometimes I pack my files without error message, but if I open the blend-file on another machine the packed files aren’t there for some reason.
My question now is there any view available where I can see at one sight which files are packed and which not?
The option ‘find missing file’ does not really help.

So I need a tool inside blender where I can manage my missing files more user friendly.

Is there such a tool available?

Thanks for any help!