diff --git a/src/tilecache.js b/src/tilecache.js
index 6839e15a..2b7575a5 100644
--- a/src/tilecache.js
+++ b/src/tilecache.js
@@ -1132,6 +1132,24 @@
             }
         }
 
+        /**
+         * Delete all data in the cache
+         * @param {boolean} withZombies
+         */
+        clear(withZombies = true) {
+            for (let zombie in this._zombiesLoaded) {
+                this._zombiesLoaded[zombie].destroy();
+            }
+            for (let tile in this._tilesLoaded) {
+                this._unloadTile(tile, true, undefined);
+            }
+            this._tilesLoaded = [];
+            this._zombiesLoaded = [];
+            this._zombiesLoadedCount = 0;
+            this._cachesLoaded = [];
+            this._cachesLoadedCount = 0;
+        }
+
         /**
          * Returns reference to all tiles loaded by a particular
          * tiled image item
diff --git a/src/viewer.js b/src/viewer.js
index 4450158c..f3be8102 100644
--- a/src/viewer.js
+++ b/src/viewer.js
@@ -812,6 +812,7 @@ $.extend( $.Viewer.prototype, $.EventSource.prototype, $.ControlDock.prototype,
         THIS[ this.hash ].animating = false;
 
         this.world.removeAll();
+        this.tileCache.clear();
         this.imageLoader.clear();
 
         /**
diff --git a/src/webgldrawer.js b/src/webgldrawer.js
index 624f3937..536c264d 100644
--- a/src/webgldrawer.js
+++ b/src/webgldrawer.js
@@ -374,14 +374,15 @@
                     // iterate over tiles and add data for each one to the buffers
                     for(let tileIndex = 0; tileIndex < tilesToDraw.length; tileIndex++){
                         let tile = tilesToDraw[tileIndex].tile;
-                        const textureInfo = this.getDataToDraw(tile);
-                        if (!textureInfo) {
-                            continue;
-                        }
-
                         let indexInDrawArray = tileIndex % maxTextures;
                         let numTilesToDraw =  indexInDrawArray + 1;
-                        this._getTileData(tile, tiledImage, textureInfo, overallMatrix, indexInDrawArray, texturePositionArray, textureDataArray, matrixArray, opacityArray);
+                        const textureInfo = this.getDataToDraw(tile);
+
+                        if (textureInfo) {
+                            this._getTileData(tile, tiledImage, textureInfo, overallMatrix, indexInDrawArray, texturePositionArray, textureDataArray, matrixArray, opacityArray);
+                        } else {
+                            // console.log('No tile info', tile);
+                        }
 
                         if( (numTilesToDraw === maxTextures) || (tileIndex === tilesToDraw.length - 1)){
                             // We've filled up the buffers: time to draw this set of tiles
diff --git a/src/world.js b/src/world.js
index a2836028..737b6760 100644
--- a/src/world.js
+++ b/src/world.js
@@ -270,6 +270,10 @@ $.extend( $.World.prototype, $.EventSource.prototype, /** @lends OpenSeadragon.W
      * @return {OpenSeadragon.Promise<?>}
      */
     requestTileInvalidateEvent: function(tilesToProcess, tStamp, restoreTiles = true, _allowTileUnloaded = false) {
+        if (!this.viewer.isOpen()) {
+            return $.Promise.resolve();
+        }
+
         const tileList = [],
             markedTiles = [];
         for (const tile of tilesToProcess) {
@@ -372,7 +376,7 @@ $.extend( $.World.prototype, $.EventSource.prototype, /** @lends OpenSeadragon.W
             return eventTarget.raiseEventAwaiting('tile-invalidated', {
                 tile: tile,
                 tiledImage: tiledImage,
-                outdated: () => originalCache.__invStamp !== tStamp,
+                outdated: () => originalCache.__invStamp !== tStamp || (!tile.loaded && !tile.loading),
                 getData: getWorkingCacheData,
                 setData: setWorkingCacheData,
                 resetData: () => {
@@ -382,7 +386,7 @@ $.extend( $.World.prototype, $.EventSource.prototype, /** @lends OpenSeadragon.W
                     }
                 }
             }).then(_ => {
-                if (originalCache.__invStamp === tStamp) {
+                if (originalCache.__invStamp === tStamp && (tile.loaded || tile.loading)) {
                     if (workingCache) {
                         return workingCache.prepareForRendering(drawerId, supportedFormats, keepInternalCacheCopy).then(c => {
                             if (c && originalCache.__invStamp === tStamp) {
diff --git a/test/modules/formats.js b/test/modules/formats.js
index 6b5c7fb6..bd851b92 100644
--- a/test/modules/formats.js
+++ b/test/modules/formats.js
@@ -29,7 +29,7 @@
     };
 
     var testOpen = function(tileSource, assert) {
-        var timeWatcher = Util.timeWatcher(assert, 7000);
+        const done = assert.async();
 
         viewer = OpenSeadragon({
             id:            'example',
@@ -56,7 +56,7 @@
             viewer.removeHandler('close', closeHandler);
             $('#example').empty();
             assert.ok(true, 'Close event was sent');
-            timeWatcher.done();
+            done();
         };
         viewer.addHandler('open', openHandler);
     };