[NiLuJe]

This patch will allow us to see who's calling prevent/allow, which should help tracking down the misbehaving code...

diff --git a/frontend/ui/uimanager.lua b/frontend/ui/uimanager.lua
index 3a0cb8860..6acd3748b 100644
--- a/frontend/ui/uimanager.lua
+++ b/frontend/ui/uimanager.lua
@@ -1823,6 +1823,7 @@ Called once we're done with whatever we were doing in the background.
 Standby is re-enabled only after all issued prevents are paired with allowStandby for each one.
 ]]
 function UIManager:allowStandby()
+    logger.dbg("UIManager:allowStandby:", debug.traceback())
     assert(self._prevent_standby_count > 0, "allowing standby that isn't prevented; you have an allow/prevent mismatch somewhere")
     self._prevent_standby_count = self._prevent_standby_count - 1
 end
@@ -1833,6 +1834,7 @@ Prevent standby.
 i.e., something is happening in background, yet UI may tick.
 ]]
 function UIManager:preventStandby()
+    logger.dbg("UIManager:preventStandby:", debug.traceback())
     self._prevent_standby_count = self._prevent_standby_count + 1
 end