If you upgraded the Editor plugin to 1.0.2 or later you also have to upgrade the Srcset/Lazysrcset plugin to 3.3.2 or later.
The error by the old srcset plugin version will cause the value of the editor to be null thus removing your inputted data on a page save. Once upgraded the the srcset plugin will behave as expected again.
Maybe the community admins could pin this thread for a few days? thanks.