diff --git a/HISTORY.md b/HISTORY.md
index 1ffb148..aedcabb 100644
--- a/HISTORY.md
+++ b/HISTORY.md
@@ -3,6 +3,11 @@
 https://github.com/josdejong/jsoneditor
 
 
+## not yet released, version 5.28.1
+
+- Fix #638: cannot expand after collapse. Regression introduced in v5.28.0.
+
+
 ## 2019-01-21, version 5.28.0
 
 - Implemented new option `maxVisibleChilds` to customize the maximum number
diff --git a/src/js/Node.js b/src/js/Node.js
index 4d4405f..ee1b178 100644
--- a/src/js/Node.js
+++ b/src/js/Node.js
@@ -910,7 +910,7 @@ Node.prototype.hideChilds = function(options) {
 
   // reset max visible childs
   if (!options || options.resetVisibleChilds) {
-    delete this.visibleChilds;
+    this.visibleChilds = this.getMaxVisibleChilds();
   }
 };
 /**