diff --git a/indra/newview/llfloatereditenvironmentbase.cpp b/indra/newview/llfloatereditenvironmentbase.cpp
index cd24d79b7f7968c9f3b5e30cd745d435e80e8658..e7e0ff717ec3de5d7b32d68b2ed8a37e24e61cbf 100644
--- a/indra/newview/llfloatereditenvironmentbase.cpp
+++ b/indra/newview/llfloatereditenvironmentbase.cpp
@@ -47,6 +47,7 @@
 
 #include "llsettingsvo.h"
 #include "llinventorymodel.h"
+#include "pipeline.h"
 
 namespace
 {
@@ -106,6 +107,9 @@ void LLFloaterEditEnvironmentBase::onFocusReceived()
     {
         updateEditEnvironment();
         LLEnvironment::instance().setSelectedEnvironment(LLEnvironment::ENV_EDIT, LLEnvironment::TRANSITION_FAST);
+
+        // HACK -- resume reflection map manager because setSelectedEnvironment may pause it (SL-20456)
+        gPipeline.mReflectionMapManager.resume();
     }
 }
 
diff --git a/indra/newview/llfloaterenvironmentadjust.cpp b/indra/newview/llfloaterenvironmentadjust.cpp
index f3133ecb37baf9ca2ebde536b501dfd0e3d0c960..c64ee5a69ceaa512ee51c9749e25542e7d4e44b5 100644
--- a/indra/newview/llfloaterenvironmentadjust.cpp
+++ b/indra/newview/llfloaterenvironmentadjust.cpp
@@ -36,6 +36,7 @@
 #include "llvirtualtrackball.h"
 #include "llenvironment.h"
 #include "llviewercontrol.h"
+#include "pipeline.h"
 
 //=========================================================================
 namespace
@@ -134,6 +135,9 @@ void LLFloaterEnvironmentAdjust::onOpen(const LLSD& key)
 
     mEventConnection = LLEnvironment::instance().setEnvironmentChanged([this](LLEnvironment::EnvSelection_t env, S32 version){ onEnvironmentUpdated(env, version); });
 
+    // HACK -- resume reflection map manager because "setEnvironmentChanged" may pause it (SL-20456)
+    gPipeline.mReflectionMapManager.resume();
+
     LLFloater::onOpen(key);
     refresh();
 }