Anansi Macro keys not mappable in Synapse 3.4.513.51410

When attempting to bind a macro to a key, it says "Choose a device to bind to" and lists the macro name as well as the cancel and save buttons but there is nothing else to click on to select the key to bind to. Hitting the macro keys with or without having fn+alt(m) held down does nothing. Can anyone help? TIA