Here's our module intializer:

define([
// Dojo
    "dojo",
    "dojo/_base/declare",
    "dojo/aspect",
//CMS    
    "epi/_Module",
    "epi/dependency",
    "epi/routes",
//PhoenixCMS
    "phoenixcms/Commands/ScaffoldCommand",
    "phoenixcms/Commands/CMSHelpCommand"
    ],
    function (
    // Dojo    
        dojo,
        declare,
        aspect,
    //CMS    
        _Module,
        dependency,
        routes,
        ScaffoldCommand,
        CMSHelpCommand
        ) {

        return declare([_Module], {
            // summary: Module initializer for the default module.         
            initialize: function () {
                this.inherited(arguments);

                //Register the store
                var storeregistry = this.resolveDependency("epi.storeregistry");
                storeregistry.create("phoenixcms.testreststore", this._getRestPath("TestRestStore"));
                storeregistry.create("phoenixcms.bbbtagreststore", this._getRestPath("BBBTagRestStore"));
                storeregistry.create("phoenixcms.bbbbundlecodereststore", this._getRestPath("BBBBundleCodeRestStore"));
                storeregistry.create("phoenixcms.givetagreststore", this._getRestPath("GiveTagRestStore"));
                storeregistry.create("phoenixcms.givebundlecodereststore", this._getRestPath("GiveBundleCodeRestStore"));
                storeregistry.create("phoenixcms.bbbbaselinescheduledscaffoldreststore", this._getRestPath("BBBBaselineScheduledScaffoldRestStore"));

                //Register global toolbar commands
                var handle,
                    registry = dependency.resolve("epi.globalcommandregistry"),
                    callback = function (identifier, provider) {

                        if (identifier == "epi.cms.globalToolbar") {  
                            provider.addCommand(new ScaffoldCommand(), { showLabel: true, id: "ScaffoldCommand" });
                            provider.addCommand(new CMSHelpCommand(), { showLabel: true, id: "CMSHelpCommand" });
                        }
                        else {
                            return;
                        }

                        handle.remove();
                        
                    };

                handle = aspect.after(registry, 'registerProvider', callback, true);
            },

            _getRestPath: function (name) {
                return routes.getRestPath({ moduleArea: "app", storeName: name });
            }
        });
    });

I'll also note that our nuget packages for:

Episerver.CMS.UI, Episerver.CMS.UI.Core, and Episerver.CMS.UI.Sources are all 8.2.1

Hi, Did you find any solution for this? I have exactly the same problem.

// Regards