When Localytics reports “[Unspecified]” in the dashboard for a specific Custom Dimension, it means Localytics has received a NULL value for that dimension. In other words, when the custom dimension was triggered, no known value had been assigned for that dimension in your app. We report this as “[Unspecified]” to distinguish from cases where a customer might prefer to deliberately pass the value of “NULL”.
Whenever a datapoint is created, all custom dimension values are attached to the datapoint. Therefore, it is ideal to set custom dimensions as soon as their value is known in all code paths in your app even if you only set the value to “Not applicable” or “Not available”.
*** “[Unspecified]” often occurs during the Session Start data point. Therefore, it is not uncommon to use analytics callbacks (iOS / Android) to set custom dimension values before the start of a session (and the creation of a “session start” datapoint).