fix(segmentation): Changes to fix problems with non hydrated/loaded segmentations to be viewable when switching hanging protocols (e.g. MPR) (#5139)

extensions/default/src/utils/layerConfigurationUtils.ts

@@ -65,15 +65,23 @@ export function configureViewportForLayerAddition(params: {
     viewport.viewportOptions.orientation = cornerstoneViewportService.getOrientation(viewportId);
   }
 
-  // Do not force volume for SEG and RTSTRUCT if there is only one display set
-  if (requestedLayerDisplaySet.isOverlayDisplaySet && currentDisplaySetUIDs.length === 1) {
-    viewport.viewportOptions.viewportType = 'stack';
-  } else {
-    viewport.viewportOptions.viewportType = 'volume';
+  // If a viewport type was already set do not reset it.
+  if (!viewport.viewportOptions.viewportType) {
+    // Do not force volume for SEG and RTSTRUCT if there is only one display set
+    if (requestedLayerDisplaySet.isOverlayDisplaySet && currentDisplaySetUIDs.length === 1) {
+      viewport.viewportOptions.viewportType = 'stack';
+    } else {
+      viewport.viewportOptions.viewportType = 'volume';
+    }
   }
 
   // create same amount of display set options as the number of display set UIDs
   const displaySetOptions = allDisplaySetInstanceUIDs.map((uid, index) => {
+    // There is already a display set option for this display set, so return it.
+    if (viewport.displaySetOptions?.[index]) {
+      return viewport.displaySetOptions[index];
+    }
+
     if (index === 0) {
       // no colormap for background
       return {};