Calendar entries only in Sophos Secure Email own Calendars
Currently it is able to optionally display non-SSE calendars inside SSE, which is great for organise corporate events with private events.
But if you have enabled this option and want to create a new calendar entry in SSE under some circumstances not only the SSE calendars are selectable as the "destination calendar" but also some device/other app calendars (see escalated case 9062033).
Obviously if you select a non SSE calendar no entry will be created.
So in our opinion it should never available for selection and this should be achieved not by filtering out non SSE calendars, but to include only SSE calendars (more reliable).
is your request for iOS or Android and are you using the latest version of the app? We had an issue last year on Android but fixed the issue in our September release