Thanks for reporting this issue, with our apologies for the trouble.
This appears to be a new bug that crept in when our Devs recently fixed another long-standing bug, where attempting to add a new Discount Code that already exists applied to the same thing -- e.g., duplicate codes applied to the Cart Item Total, or duplicate codes applied to the Item Unit Price of the same product -- would appear to succeed, but actually fail due to that duplication which is not allowed.
Adding error feedback to inform users when and why a duplicate was blocked required some back-end programming changes that inadvertently introduced this new bug affecting the ability to add duplicate codes that are permitted when they apply to different things, as well as issues in displaying the settings of existing discounts named with any non-alphanumeric symbols (e.g.
- & % ( )).
Meanwhile, at present the only way to have a single Discount Code that can apply to multiple products would be to make it a Cart Item Total discount. There's no way to exclude products from that type of discount, so you might consider temporarily raising the price of items you don't want discounted, to offset this blanket discount on the Cart Item Total.
We'll followup here to let you know when our Devs have fixed this new problem.