Custom basemap (with opaque symbology) in ArcGIS Field Maps mobile apps is not visible when the mobile device is set to dark mode. This issue only appears on Android mobile devices.
This issue is non-reproducible in ArcGIS Field Map. If this issue persists, contact Esri Support Services as additional information is needed for further investigation.
解决办法
Set the mobile device settings to turn off the dark mode and allow the features to be seen as expected in ArcGIS Field Maps.
Update the opaque symbology in the custom basemap to ensure all features can been viewed as expected.