If you enable explore to all modules and then you enable the explore feature. after upgrading the app, all soruces are deselected and the user has to figure it out and go into explore to enable.
Is your Explore module first one on the Left Menu? if so, move it to the second or more in the list. when application first open, it open the first module in the Left Menu, at the same time, we will try to fix it in future release.