Having an ISV solution developed and exported from an on-premise instance as a "managed" solution (8.2), there is no option available to set entity managed properties "Can enable sync to external search index". After managed solution is imported to an online environment (8.2), the newly added entity managed property "Can enable sync to external search index" is read-only and cannot me set to True. The custom entity is set to fully "Customizable".
This would appear to be a major oversight. What options are available to set this property?
Also, can anyone confirm that relevance search is enabled for sandbox environments?