matt on 24 May, 2018 02:08 AM
I'm sorry but the data is gone, you have to re-create it.
Normally any unsaved data should get retained while you sign in, after which you can click the save icon again and save the map. However it looks like there's a recently introduced bug causing this data to get kept - you'd need to sign in first, before creating anything. I'll try to fix it soon.