SUMMARY
cannot copy coordinates from map

STEPS TO REPRODUCE
see digikam documentation 
5.1.2  Edit Coordinates
The coordinates can be set manually in the Details tab (see screenshot above). The location can
be found and fixed iteratively with the displayed map. Move the mouse cursor to the region of
interest, zoom in, adjust location, zoom in again, and so on until sufficient accuracy is achieved.
Note that the zoom center will always be at the cursor position. Eventually you click with the
right mouse button at the desired position and choose Copy Coordinates. Now you can go to
the list of images below the map, select one or more images, click with the right mouse button on
them and choose Paste Coordinates. The coordinates will then be displayed in the Latitude and
Longitude fields to the right of the map. To save your changes you click the Apply button right
under the DOP field.
The coordinates can be set manually in the Details tab (see screenshot above). The location can
be found and fixed iteratively with the displayed map. Move the mouse cursor to the region of
interest, zoom in, adjust location, zoom in again, and so on until sufficient accuracy is achieved.
Note that the zoom center will always be at the cursor position. Eventually you click with the
right mouse button at the desired position and choose Copy Coordinates. Now you can go to
the list of images below the map, select one or more images, click with the right mouse button on
them and choose Paste Coordinates. The coordinates will then be displayed in the Latitude and
Longitude fields to the right of the map. To save your changes you click the Apply button right
under the DOP field.


OBSERVED RESULT


EXPECTED RESULT
this works in 5.6.0 on KDE software opensuse 42.3 as below

SOFTWARE VERSIONS on opensuse leap 42.3
(available in About System)
KDE Plasma Version: 5.8.7
KDE Frameworks Version: 5.32.0
Qt Version: 5.6.2

ADDITIONAL INFORMATION
same problem on opensuse leap 15.0
KDE Plasma Version: 5.12.5
KDE Frameworks Version: 5.45.0
Qt Version: 5.9.4


I've seen this problem many years ago..... then it was fixed till now.