Server Didn't Save

So yesterday I played for 7 hours straight with my friends on my server, did a bunch of looting and exploration, and worked for hours on my base. I stopped the server in the end. No plugins, no overload - just pure Minecraft. This morning I started the server again and all the data was lost. I didn't have backups, unfortunately, but now I can't even start over because it is not even for sure that the server will be saved. I have been using Aternos forever and it is the first time such a thing happened. I hope someone will be able to help, or at least make an explanation of why this happened at all in the first place.

I didn't know that there was an ongoing issue. Thank you for your time and information.