diff --git a/dsv4/kernels/attention/fmha_6warp_tma_multirow_multitile.cuh b/dsv4/kernels/attention/fmha_6warp_tma_multirow_multitile.cuh
index f5fc8b18..56dbdabf 100644
--- a/dsv4/kernels/attention/fmha_6warp_tma_multirow_multitile.cuh
+++ b/dsv4/kernels/attention/fmha_6warp_tma_multirow_multitile.cuh
@@ -130,6 +130,15 @@ fmha_6warp_tma_multirow_multitile_kernel(FmhaTmaMultiRowMultiTileParams params)
         const int n_sub_end = n_sub_start + N_NSUB_CHUNK;
         int phase = 0;  // reset mbarrier phase per hd_chunk
 
+        // DEBUG: skip hd_chunk > 0 to test just chunk 0
+        if (hd_chunk > 0) {
+            if (my_row_active) {
+                for (int d = 0; d < HD_CHUNK; d++)
+                    o_head[my_row * HD + hd_chunk_start + d] = f32_to_bf16(0.0f);
+            }
+            continue;
+        }
+
         // Zero accumulator
         for (int i = tid; i < MAX_ROWS * HD_CHUNK; i += 192) sOacc[i] = 0.0f;
         for (int i = tid; i < MAX_ROWS; i += 192) {
@@ -330,6 +339,13 @@ fmha_6warp_tma_multirow_multitile_kernel(FmhaTmaMultiRowMultiTileParams params)
         // ---- Write chunk to GMEM ----
         if (my_row_active) {
             float inv_rs = 1.0f / sRunningSum[my_row];
+            // Debug: for first hd_chunk, first row, print some values
+            if (my_row == 0 && hd_chunk == 0) {
+                // Print first 8 O values and running stats
+                printf("hd_chunk=%d rmax=%f rsum=%f O[0..3]=%f %f %f %f\n",
+                    hd_chunk, sRunningMax[0], sRunningSum[0],
+                    sOacc[0] * inv_rs, sOacc[1] * inv_rs, sOacc[2] * inv_rs, sOacc[3] * inv_rs);
+            }
             for (int d = 0; d < HD_CHUNK; d++) {
                 o_head[my_row * HD + hd_chunk_start + d] = f32_to_bf16(sOacc[my_row * HD_CHUNK + d] * inv_rs);
             }