So to update: a hotfix of The Events Calendar 2.0.9 was made available in the WordPress plugin directory that addressed some recent issues.
Unfortunately the developers were unable to consistently replicate the problem that many of you have described (settings resetting to “factory default”) so we can’t be 100% certain that the issue is resolved, though we are hopeful.
Once again please accept our apologies for any inconvenience – we’ve certainly taken your feedback and concerns on board.