Hi there,
Really glad to see Groups have been added into the legend in Map Viewer!
I have a lot of values to add, and I noticed they're not all appearing or able to come out of Other... is there a limitation to the number of items you can have in the legend?
Map Viewer and Map Viewer Classic currently limit the list to 200 unique types and then the rest of the values will end up under the Other category. You could publish the layer from Pro with the 335 values out of other but you might see some performance issues when the list is being generated. ArcGIS Pro 3.2 coming later this year will support publishing maps with the Types grouping as well. We are also working on bulk actions to make grouping easier and faster in Map Viewer.