This can be a bit tricky to solve as there are a lot of things that can create this issue. I'll list some of the most common things that can cause this and you should hopefully be able to get it resolved quickly!
If you are still not able to find the issue please don't hesitate to reach out to our live support for additional help with this. To contact our live support please follow this link: Shopify Help Center - Contact Support, sign into your store account, search for your issue and use the contact support button at the bottom of the search results to see all our live support options.
We don't have a direct link I can provide as you need to go through the Help Center to ensure you receive the contact information for the right support team. When you follow this link: Shopify Help Center - Contact Support you will be asked to sign into your store account. You will then be asked to search for your issue in the Help Center. At the bottom of the search results there will be a contact support button you can use to see all the available support options we have.
If that isn't working for you, please take a screenshot of the last step you are able to get to and I will help you troubleshoot.
Great! I am glad you were able to get that resolved and thank you for your reply letting us know what the problem was. This will really help future merchants in the same situation.