Hi rocksolidav,

Your client may be experiencing some browser-related issues when paying invoices. Let's fix it by performing some steps. 

Before doing so, can you share a screenshot of the buttons that you're clients are seeing when paying invoices?

In the meantime, let's fix this by performing some troubleshooting steps. To begin with, let them log into an incognito window and pay the transaction from there. They can use these keyboard keys to open one:

• Google Chrome: Ctrl + Shift + N
• Microsoft Edge & Mozilla Firefox: Ctrl + Shift + P
• Safari: Control + Option + P

If they're able to get rid of the mentioned buttons, they can continue paying invoices on a regular browser and clear its cache. Piled cache can also be the reason for some unexpected issues on the opened pages. 

They can also switch to a different browser like Google Chrome, Mozilla Firefox, Microsoft Edge, or Safari.

Furthermore, I've added this reference on how you can manage electronic payments: Take and process payments online.

Don't hesitate to get back to us whenever you have