fix multi-collection bug (#318)

CHANGELOG.md

@@ -8,6 +8,9 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 - Add multiple local libraries to better organize your media
 - Add `Move Library Path` function to support reorganizing existing local libraries
 
+### Fixed
+- Fix bug preventing playouts from rebuilding after an empty collection is encountered within a multi-collection
+
 ## [0.0.51-alpha] - 2021-07-18
 ### Added
 - Add `Multi Collection` to support shuffling multiple collections within a single schedule item

ErsatzTV.Core/Scheduling/MultiCollectionGrouper.cs

@@ -1,4 +1,5 @@
 using System.Collections.Generic;
+using System.Linq;
 
 namespace ErsatzTV.Core.Scheduling
 {
@@ -8,7 +9,7 @@ namespace ErsatzTV.Core.Scheduling
         {
             var result = new List<GroupedMediaItem>();
 
-            foreach (CollectionWithItems collection in collections)
+            foreach (CollectionWithItems collection in collections.Where(collection => collection.MediaItems.Any()))
             {
                 if (collection.ScheduleAsGroup)
                 {