I am porting over to v4. Fun! (not.)

My scrollbars are disappearing from my grid panel after reloading it.

Here is the code the creates the grid:

Code:
        var sitesData = { "records": [{
            id: "12893", 
            lat: "47.3004", 
            lng: "-122.225",
            type: "2~8",
            listTypes: "LUST~UST",
            siteName: "CENEX HARVEST STATES COOPERATIVES",
            riskLevel: "2",
            street: "238 8TH SE",
            city: "AUBURN",
            state: "WA",
            ZIP: "98002",
            siteids: "WALUSTIS-2487~WAUSTLIS-2487"
        }],
        success: true,
        totalCount: 1
        };


        Ext.define('Record', {
            extend: 'Ext.data.Model',
            fields: [
                    {name: "id", type: 'string'}, 
                    {name: "lat", type: 'float'}, 
                    {name: "lng", type: 'float'}, 
                    {name: "type", type: 'string'}, 
                    {name: "listTypes", type: 'string'}, 
                    {name: "siteName", type: 'string'}, 
                    {name: "riskLevel", type: 'string'}, 
                    {name: "street", type: 'string'}, 
                    {name: "city", type: 'string'}, 
                    {name: "state", type: 'string'}, 
                    {name: "ZIP", type: 'string'}, 
                    {name: "siteids", type: 'string'}
            ]
        });
        
        var gridStore = Ext.create('Ext.data.Store', {
            autoLoad: true,
            model: 'Record',
            data: sitesData,
            proxy: {
                type: 'memory',
                reader: {
                    type: 'json',
                    root: 'records',
                    totalProperty: 'totalCount'
                }
            }
        });
        
        this.activeDetailsGrid = {
            xtype: 'grid',
            store: gridStore,
            selType: 'rowmodel',
            autoScroll: true,
            id: 'grid-panel',
            columns: [
                  { id: 'subjectHit', header: "S", width: 25, sortable: true, renderer: Layout.subjectHit, dataIndex: 'subjectHit' },
                  { id: 'id', header: "Site ID", width: 50, sortable: true, dataIndex: 'id' },
                  { text: "Site Name", width: 150, sortable: true, dataIndex: 'siteName' },
                  { text: "Street", width: 150, sortable: true, dataIndex: 'street' },
                  { text: "City", width: 75, sortable: true, dataIndex: 'city' },
                  { text: "ST", width: 30, sortable: true, dataIndex: 'state' },
                  { text: "ZIP", width: 50, sortable: true, dataIndex: 'ZIP' },
                  { text: "Risk", width: 50, sortable: true, dataIndex: 'riskLevel', renderer: Layout.checkRiskLevel},
                  { text: "Site Types", width: 125, sortable: true, dataIndex: 'listTypes' },
            ]
        };
I am using the sitesData var is used to provide some data to create the grid. This is a holdover from v3.x - may not be needed in v4?

I have a horizontal scrollbar as expected.

Then I create my real data in a new sitesData variable and call this:

Code:
Layout.activeDetailsGrid.store.loadRawData(sitesData);
My data in loaded into the grid as expected, but the scrollbars disappear. I should have both scrollbars.

Any clues why this is happening? I am using 4.0.7.

Thanks!
Brad