Hi there, @IvaniQK.
I appreciate doing troubleshooting steps on your end to get rid of the issue. The correct rates conversion of your invoices is my priority, so I'll point you in the right direction.
With this, I'd suggest communicating to the Zappier support to verify if they have any issues or updates on their side. If they don't have one, please reach out to our Customer Care Team. They can take a look at your account in a protected situation and investigate the root cause of the problem.
Here's how:
- Go to the Help menu, then choose Contact Us.
- Type your concern in the box, then hit Let's talk.
- Choose either Get a call or Start a chat.

4. Complete the obliged information, then submit the request.
Please call our support within business hours to ensure we address your concern directly. For more details, check out this article: Contact QuickBooks products and services Support.
I'm including these articles below to learn more about how multi-currency works in the program:
Let me know how the call goes and if you have other questions. I'm pleased to assist. Take care!