Trying to figure out what I'm missing because the SDK documentation isn't quite explaining it. I'm trying to consolidate commands in my add-in to reduce the window pane dancing so I have an "edit" group where I've incorporated many of the standard edit tools. In the DAML it's set up like such:
<group id="Editing_Tools" caption="Editing Tools" appearsOnAddInTab="true" keytip="ET">
<button refID="esri_mapping_selectToolPalette" size="large"/>
<button refID="esri_mapping_clearSelectionButton" size="large"/>
<button refID="esri_editing_ShowAttributes" size="large"/>
<buttonPalette refID="Editing_Tool_Commands" size="large"/>
<button refID="esri_editing_SaveEditsBtn" size="large"/>
<button refID="esri_editing_DiscardEditsBtn" size="large"/>
<button refID="esri_geoprocessing_toolsButton" size="large"/>
</group>
In the middle, you can see I'm using a buttonPalette to group together can save some screen real estate. The buttonPalette has been set up like this:
<palettes>
<buttonPalette id="Editing_Tool_Commands" caption="Edit Operations" dropDown="true" menuStyle="true" showItemCaption="false" keytip="BP">
<button refID="esri_editing_EditVerticesMove"/>
<button refID="esri_editing_EditVerticesRotate"/>
<button refID="esri_editing_EditVerticesScale"/>
<button refID="esri_editing_EditVerticesModifyFeature" separator="true"/>
<button refID="esri_editing_ReplaceGeometry"/>
<button refID="esri_editing_ExtendTrimFeatures"/>
<button refID="esri_editing_LineIntersection"/>
<button refID="esri_editing_SplitCommand" separator="true"/>
<button refID="esri_editing_ClipCommand"/>
<button refID="esri_editing_ExplodeFeatures"/>
<button refID="esri_editing_MergeFeatures" separator="true"/>
<button refID="esri_editing_BufferFeatures"/>
<button refID="esri_editing_CopyParallel"/>
</buttonPalette>
</palettes>
I've specified the separator="true" option on a few entries so that the dropdown would show a divider between groups of edit tools. Unfortunately, when I get into Pro, the menu looks like this:

None of the separators show up, so I'm wondering what I have set up incorrectly. The SDK discusses the concept of split buttons but it's unclear if those work with buttonPalettes. I get the impression from VS that it is not part of buttonPalettes. It *seems* like it is supported if you look at some of the default tools like the Explore Tool so I'm just confused how it actually gets implemented.

Thanks!
Steve