An existing Fontwork object in a document in Writer cannot be selected.

Try this:

(1) Create a new text document.
(2) Create any Fontwork object, move and place it in your document.
(3) Deselect the Fontwork object.
(4) Try to reselect the object.
--> There seems to be no way to select the object.

Workaround:
* Create the Fontwork object in an other component, for example Calc
* Copy & Paste the object into Writer
--> This object can be selected, deselected ans reselected as expected.