index was into cgpu threads, not into global mining threads

driver-opencl.c

@@ -683,7 +683,7 @@ void pause_dynamic_threads(int gpu)
   for (i = 1; i < cgpu->threads; i++) {
     struct thr_info *thr;
 
-    thr = mining_thr[i];
+    thr = cgpu->thr[i];
     if (!thr->pause && cgpu->dynamic) {
       applog(LOG_WARNING, "Disabling extra threads due to dynamic mode.");
       applog(LOG_WARNING, "Tune dynamic intensity with --gpu-dyninterval");