Query results depend on filters and time range. Depending on how the Azure Monitor workbook was built it can offer choosing time range and different filters. Azure dashboards have way less capabilities than Azure Monitor workbooks. For example, there you do not have filters. You only have time range that you can choose from the top of the dashboard. Check may be if the time filter on your workbook is the same as the one on the dashboard. Keep in mind that the pin tile can honor the time range selected on the Azure Dashboard or have its own static time range that you can only change if you edit the dashboard and customize the tile.
In short Azure Dashboards are not as so functional as Azure Monitor workbook so depending on the filters and time ranges they can show different results but that is limit due to using Dashboards not a problem with the data.
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