Hi all.
There is no reason we are aware of where the import process should be functional at one point, and then suddenly begin giving this error on the same machine.
Generally, this error will occur if you are experiencing a network issue, or if you have security features on your system that may block the network traffic. See https://unrealstudiohelp.epicgames.com/s/article/Network-Connectivity-Troubleshooting. Naturally this causes me to feel like something must have changed regarding your system during the day, although I am also aware that seems unlikely.
We did attempt to design for possibilities such as this by having the editor remember your previous successful imports and not trigger this error message for a set amount of time, however we have identified that there are some issues with that functionality. Improvements are being made for the 4.21 release.
We are not aware of any issues with our entitlement service at the moment. My primary suggestion would be for you to restart the Epic Games Launcher and the Editor, although it seems that you have tried that.
Apologies for the inconvenience.