Why are some labels not displayed at different map extents in ArcGIS Online Map Viewer Classic compared to ArcGIS Online Map Viewer?

Answer

When the labels in a web map are configured using ArcGIS Online Map Viewer, opening the same web map in Map Viewer Classic displays the labels differently. In some cases, the cluster labels are not visible or display in shifted positions at different map extents. The image below shows the labels in Map Viewer are not displayed when opened in Map Viewer Classic.

In ArcGIS Online Map Viewer

In ArcGIS Online Map Viewer Classic

Due to the different JavaScript API versions, labels configured in Map Viewer display differently on the map in Map Viewer Classic. Map Viewer and newer apps (such as ArcGIS Experience Builder) use ArcGIS Maps SDK for JavaScript 4.x (formerly known as ArcGIS API for JavaScript 4.x), whereas Map Viewer Classic and older apps (such as ArcGIS Web AppBuilder) use ArcGIS API for JavaScript 3.x.

Certain cluster labels are not visible or display in shifted positions at different zoom levels when viewed in Map Viewer Classic or apps that use ArcGIS API for JavaScript 3.x compared to Map Viewer and apps that use ArcGIS Maps SDK for JavaScript 4.x. This discrepancy is a known limitation as new capabilities such as labeling clusters are only available in Map Viewer. Refer to ArcGIS Online: Maps for the capabilities available in Map Viewer.

Although changing the label style (for example, decreasing the font size) can change the way in which the labels are displayed for apps that use ArcGIS API for JavaScript 3.x, there is no way to fully work around this limitation.