diff --git a/engine/MUNGA/GAUGREND.cpp b/engine/MUNGA/GAUGREND.cpp
index 56eaf30..bc507bc 100644
--- a/engine/MUNGA/GAUGREND.cpp
+++ b/engine/MUNGA/GAUGREND.cpp
@@ -3702,8 +3702,19 @@ void
 	// like the pod -- and the working SetPresetMode page switching NEEDS the
 	// authentic gating (the force made every eng screen paint over the shared
 	// Eng plane, pinning it on the highest screen and ignoring page flips).
+	// (BT411 #155, 2026-08-14) READ OUR OWN LAST-FRAME MASK, not the mode
+	// manager's previousModeMask: that cell is a shared scratch overwritten by
+	// EVERY Add/RemoveModeMask call, and the authentic panic-arm chatter (the
+	// no-hysteresis eject evaluator) writes it per frame -- stomping the page
+	// bits out of this XOR before we sample it.  Result in the field: MFD page
+	// EXITS went dead while PANIC flickered (first entries still worked via
+	// !alreadyActivatedFlag), radar/score/coolant stayed live (always-active).
+	// The renderer already maintains its own previousModeMask member (updated
+	// below at the activate/deactivate guard); sampling it here makes the
+	// change mask accumulate everything since the LAST RENDER FRAME, correct
+	// under any number of mode writers.  Single-transition frames: identical.
 	ModeMask
-		previous_mode_mask = application->GetModeManager()->GetPreviousModeMask();
+		previous_mode_mask = previousModeMask;
 	ModeMask
 		change_mode_mask = current_mode_mask ^ previous_mode_mask;       // xor tells me what has changed
 	//-------------------------------------------------------------------