diff --git a/CHANGELOG.md b/CHANGELOG.md
index a5e2746bf259905907116b670c94dfc676db4da7..adc4956ef518a628e152cf6dcebca3b7f292efc0 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,7 +1,8 @@
-# Version 1.28 (not yet released)
+# Version 1.28
 
 * Fixed #73: Aggregation on SQL Source does not always work
 * Fixed #40: SQL Table data source error and #45: Allow MySQL Views as Sources. See !71
+* Fixed regression bug with custom fields on activity data sources.
 
 # Version 1.27
 
diff --git a/Civi/DataProcessor/Source/AbstractCivicrmEntitySource.php b/Civi/DataProcessor/Source/AbstractCivicrmEntitySource.php
index d522fb67ff3c6e3d8bbaf702202ec8871c804a74..af14b3865eb97e7f95feb421351639e717c9ae04 100644
--- a/Civi/DataProcessor/Source/AbstractCivicrmEntitySource.php
+++ b/Civi/DataProcessor/Source/AbstractCivicrmEntitySource.php
@@ -378,13 +378,14 @@ abstract class AbstractCivicrmEntitySource extends AbstractSource {
     }
     $customGroupTableAlias = $this->getSourceName().'_'.$customGroupName;
     $this->ensureEntity(); // Ensure the entity as we need it before joining.
+    $join = new SimpleJoin($this->getSourceName(), 'id', $customGroupTableAlias, 'entity_id', 'LEFT');
+    $join->setDataProcessor($this->dataProcessor);
     if (!$this->entityJoin) {
-      $this->entityJoin = new SimpleJoin($this->getSourceName(), 'id', $customGroupTableAlias, 'entity_id', 'LEFT');
-      $this->entityJoin->setDataProcessor($this->dataProcessor);
+      $this->entityJoin = $join;
     }
     $this->customGroupDataFlowDescriptions[$customGroupName] = new DataFlowDescription(
       new SqlTableDataFlow($customGroupTableName, $customGroupTableAlias, new DataSpecification()),
-      $this->entityJoin
+      $join
     );
     $this->dataProcessor->resetDataFlow();
     return $this->customGroupDataFlowDescriptions[$customGroupName]->getDataFlow();
diff --git a/info.xml b/info.xml
index 76f6fb1be5060a6137d1939dd844dc08e5377392..9aeb6e33002dfa474f6c45aba896c61a68078ee4 100644
--- a/info.xml
+++ b/info.xml
@@ -14,8 +14,8 @@
     <url desc="Documentation">https://lab.civicrm.org/extensions/dataprocessor/blob/master/README.md</url>
     <url desc="Licensing">http://www.gnu.org/licenses/agpl-3.0.html</url>
   </urls>
-  <releaseDate>2021-01-04</releaseDate>
-  <version>1.28-dev</version>
+  <releaseDate>2021-01-12</releaseDate>
+  <version>1.28</version>
   <develStage>stable</develStage>
   <compatibility>
     <ver>4.7</ver>