I was having the same error. When submitting to Review+Create a new function app (consumption on free instance) the website would hang. Same would happen if I navigated directly to the Network tab.
The resolution, for me at least, was to add a Log Analytics Workspace to my Resource Group. After doing so the Review+Create tab for the function app loaded successfully.
I found the error by using Dev Tools (F12) and inspecting the JS error that was being thrown. I have seen at least one other forum post where the developer had a similar issue with either Storage and/org App Insights not available so check those too.