Your problem sounds different from what I've had, but maybe it is just the description?

Sometimes after I put in the RH default and then select to put in the LH default the screen refuses to show the LH default lineup or provide an option to put in the LH default.

Someone suggested right clicking on the input screen and then selecting refresh from the drop down menu.

That worked for me.

I had tried the refresh at the top of the screen, but it did not work. The right click and then refresh selection did.