Metrics with Incremental query scope need a timestamp. Depending on the timestamp format, you may have to specify the Timestamp timezone.

Timestamp

Set Timestamp to specify the column to use as your timestamp. The aggregation period for a metric is based on the value in the timestamp column, translated into the time zone specified by the Aggregation Timezone. Note that only data with timestamps prior to [now] - Evaluation Delay are collected.

• For query efficiency, when selecting a timestamp or creating a virtual timestamp based on another column, we recommend you reference an indexed/sort-keyed column.
• Some databases support enforcement of a sort-key column. If your database supports that, you will have a toggle in Query Governance called Enforce Sort Keyed Timestamps. If this is toggled on, then only sort-keyed timestamps will show in your timestamp drop-down both here in Data Collection settings, and when creating a SQL metric.
• Some timestamp columns don't include time zone information, so you might need to specify the Timezone of the timestamps. If the time zone is part of the timestamp, this setting says Derived and can't be changed.
• Note that only date or datetime columns can be selected as a timestamp— other columns will not be displayed. If no timestamp column appears as a selection but you can compute your timestamp from another column, you can create a virtual timestamp.