Hi,
I'd recommend using our Troubleshooting guide to determine what the underlying error is.
It sounds, to me, like there must be some error occurring which is causing this behavior. Unfortunately, it's impossible to provide any advice though unless we had more information on the underlying error message (likely findable either in your browser's DevTools or in the backend logs).
Once you find the underlying error, if you need more help, please send it to this list along with the steps you took to reproduce it. Hopefully that'll be enough information for us to provide you with suggestions.
Tim