I attempted to use the Fill & Sign tool and clicked add signature to add a signature stamp. I used a wacom tablet to draw a signature. The tool failed and appeared to have saved a black rectangle.

Any attempt to remove the invalid stamp have failed, clicking the (-) icon in the "Sign" dropdown menu has no effect (see screenshot).

I am now unable to sign documents in Acrobat Reader using a pen and am forced to use the text tools.

There should be workarounds to clear any existing stamps or at the least make the menu work under all circumstances