For whatever reason(s), after applying the 'Depth of Field' effect, the cloning tool no longer works properly. If I open another image, the tool works just fine but if I return to the image where the 'Depth of Field' was applied, the 'clone' no longer stays after the mouse button is released. That is, the effect seems to be temporarily applied under the brush and immediately disappears when the brush is moved or the mouse button is released?
Its the problem of layers I think. Go to Layer panel and see on which layer you are applying the Clone tool. If you wish to apply it to the complete image, you need to first Merge all the layers and then use the Clone tool.
Thanks. That helped and solved the problem.
Glad to help.