sorry for the late reply.
To fix this or rather to have the $1 bill show up in the currency counter, you have to create the $1 tender in Maintenance/Payments/Tenders.
Default amount is 1.00 and make sure to flag Cash on the Type tab.
This is really all you need to do for this to appear, you don't even have to create the button for this tender or have it flagged as active, just need the default amount and flag Cash