diff --git a/common/thorhelper/thorcommon.hpp b/common/thorhelper/thorcommon.hpp
index 2393b041301..40f9b44f566 100644
--- a/common/thorhelper/thorcommon.hpp
+++ b/common/thorhelper/thorcommon.hpp
@@ -246,12 +246,13 @@ class THORHELPER_API ActivityTimeAccumulator
     cycle_t firstExitCycles;    // Wall clock time of first exit from this activity
     cycle_t blockedCycles;  // Time spent blocked
     cycle_t lookAheadCycles;  // Time spent by lookahead thread
-
+    unsigned activeActivityTimers = 0; // Number of active activity timers
     // Return the total amount of time (in nanoseconds) spent in this activity (first entry to last exit)
     inline unsigned __int64 elapsed() const { return cycle_to_nanosec(endCycles-startCycles); }
     // Return the total amount of time (in nanoseconds) spent in the first call of this activity (first entry to first exit)
     inline unsigned __int64 latency() const { return cycle_to_nanosec(latencyCycles()); }
     inline cycle_t latencyCycles() const { return firstExitCycles-startCycles; }
+    inline unsigned queryNumActiveTimers() const { return activeActivityTimers; }
 
     void addStatistics(IStatisticGatherer & builder) const;
     void addStatistics(CRuntimeStatisticCollection & merged) const;
@@ -291,6 +292,7 @@ class ActivityTimer
                 accumulator.startCycles = startCycles;
                 accumulator.firstRow = getTimeStampNowValue();
             }
+            ++accumulator.activeActivityTimers;
         }
         else
             startCycles = 0;
@@ -306,6 +308,7 @@ class ActivityTimer
             accumulator.totalCycles += elapsedCycles;
             if (unlikely(isFirstRow))
                 accumulator.firstExitCycles = nowCycles;
+            --accumulator.activeActivityTimers;
         }
     }
 };
diff --git a/thorlcr/graph/thgraphslave.cpp b/thorlcr/graph/thgraphslave.cpp
index 7e31640b07d..67c6f049020 100644
--- a/thorlcr/graph/thgraphslave.cpp
+++ b/thorlcr/graph/thgraphslave.cpp
@@ -588,11 +588,14 @@ unsigned __int64 CSlaveActivity::queryLocalCycles() const
         }
     }
     unsigned __int64 processCycles = queryTotalCycles() + queryLookAheadCycles();
-    if (processCycles < inputCycles) // not sure how/if possible, but guard against
+    if (processCycles < inputCycles && slaveTimerStats.queryNumActiveTimers()==0) // not sure how/if possible, but guard against
+    {
+        ActPrintLog("CSlaveActivity::queryLocalCycles - process %" I64F "uns < inputCycles %" I64F "uns", cycle_to_nanosec(processCycles), cycle_to_nanosec(inputCycles));
         return 0;
+    }
     processCycles -= inputCycles;
     const unsigned __int64 blockedCycles = queryBlockedCycles();
-    if (processCycles < blockedCycles)
+    if (processCycles < blockedCycles && slaveTimerStats.queryNumActiveTimers()==0)
     {
         ActPrintLog("CSlaveActivity::queryLocalCycles - process %" I64F "uns < blocked %" I64F "uns", cycle_to_nanosec(processCycles), cycle_to_nanosec(blockedCycles));
         return 0;