Hi @side99,
Happy to help you!
Is this issue solved? If it’s not, the first thing to check is if the page defined for Success Page under Donations > Settings > General > General > Success Page is live and contains the [give_receipt] shortcode. If this page has content apart from the shortcode, I encourage you to create a fresh page with the shortcode only to test it too.
After that, please proceed to make a test donation and see if you can see the donation success page.
If it still doesn’t work, then you’d need to follow the health check tutorial. I suggest you follow our troubleshooting tutorials using Health Check. It allows you to isolate plugins and change themes for administrator, while the frontend still runs the live version of the website. You can see the documentation here:
https://givewp.com/documentation/resources/troubleshoot-wordpress-websites-health-check/
https://givewp.com/documentation/resources/how-to-troubleshoot-your-website-like-a-wordpress-support-engineer/
Let us know your findings.
Looking forward to helping you get to the bottom of this!