Am I the only user to experience no discount option on invoices even although its switched on in the sales settings?

Let's perform some troubleshooting to address your issue with the discount option not showing on your end, JCB808.

Since you’ve already enabled this feature but it’s still unavailable, I recommend clearing your browser’s cache. This will refresh your browser and eliminate any outdated data that may be affecting QuickBooks' performance.

In addition to that, your computer’s internet speed and web browser version can affect the software’s performance. To ensure a seamless experience, please make sure you’re using the latest version of your browser and have a stable internet connection.

Here's an article that you can visit if you need guidance in processing customer-based payments using QuickBooks: Record invoice payments in QuickBooks.

Feel free to comment down if you have other concerns about this.