Clone and Heal tool messed up setting?

[Ofnuts]

I can't see what you mean by "selection area within the tool", and "the little x inside the selection area". For the latter, with the "Heal" tool (but you are showing the options for the "Clone" tool), the pointer is decorated with two crossed band-aids that look like an X:

   

Otherwise, in case it is something with the image, try with another image.

Restarting Gimp is not a solution, if Gimp is set up to keep settings across sessions. See Managing tool options and window positions for details.