diff --git a/lib/network/Network.js b/lib/network/Network.js
index d43f60e4..54a0242c 100644
--- a/lib/network/Network.js
+++ b/lib/network/Network.js
@@ -273,6 +273,9 @@ Network.prototype._updateVisibleIndices = function () {
 
       if (!this.clustering._isClusteredEdge(edgeId)
         && edge.options.hidden === false
+        // Not all nodes may be present due to interim refresh
+        && nodes[edge.fromId] !== undefined
+        && nodes[edge.toId  ] !== undefined 
         // Also hidden if any of its connecting nodes are hidden
         && nodes[edge.fromId].options.hidden === false
         && nodes[edge.toId  ].options.hidden === false) {
diff --git a/lib/network/modules/PhysicsEngine.js b/lib/network/modules/PhysicsEngine.js
index 5f176a9d..2fe9b52e 100644
--- a/lib/network/modules/PhysicsEngine.js
+++ b/lib/network/modules/PhysicsEngine.js
@@ -134,6 +134,11 @@ class PhysicsEngine {
         this.physicsEnabled = false;
         this.stopSimulation();
       }
+      else if (options === true) {
+        this.options.enabled = true;
+        this.physicsEnabled = true;
+        this.startSimulation();
+      }
       else {
         this.physicsEnabled = true;
         util.selectiveNotDeepExtend(['stabilization'], this.options, options);