Marvin keeps a local copy of your data in the browser if you are using the web app. This makes accessing your data quicker and allows you to use Marvin even if there is no Internet connection. It also keeps your data safer as there are multiple copies of everything, so even if our cloud servers exploded you would have a copy of your data locally still.
When you clear your browser data, that copy gets removed.
This is only a problem if you do not have sync enabled.
Sync is on by default, so unless you turned it off yourself, it is syncing to our cloud server every time there is an Internet connection.
So if you clear your data locally, the data is still on our sync sever and will get added to the browser again when you reconnect to the sync server (almost immediately).
I can't see my data anymore!
If you cleared your browser data and can't see your data anymore, no worries. It just takes some time to load all the data from our sync server again. Wait a few minutes and all your data will return to your local browser.