Check your internet connection. Maybe something connected to your ISP or an app blocking you from contacting the cloud server. Sometimes anti-viruses and even windows defender can do that if you are using the desktop version.
For that, we can try to use the online browser version of Gravit Designer. Just follow this link.
If those aren't the cause of the issue, please send us print screens of the console and the network tabs. To do that, open the developer tools and console: on desktop app: ctrl/cmd+ shift+ F12 and on Web app: ctrl/cmd+ shift + I or alt + cmd + I on Mac (for opening developers tools) and press Esc to show Console tab.
It is important to open the console before trying to save to the cloud, otherwise, we won't be able to see what happened on the print screen. We need the console and the network tabs.