OPC 2.4.5 + Square + ZC 157c + Bootstrap
When I go to checkout, everything is fine unless I change shipping to "Store Pickup." When I do this, the credit card fields (number, expiry, cvv) change to a button labelled "Use Credit Card." Pressing this button grays the screen but doesn't reveal the fields.
The workaround I used was to change Admin > Configuration > OPC > Payment-Block Action on Shipping Change to Refresh (from Update), and this fixes it - the "Use Credit Card" button is displayed for just a second and then the fields re-appear.