diff --git a/test/python/ext/ep/test_internode_multirank.py b/test/python/ext/ep/test_internode_multirank.py
index 9ac9639c..33971cf6 100644
--- a/test/python/ext/ep/test_internode_multirank.py
+++ b/test/python/ext/ep/test_internode_multirank.py
@@ -164,15 +164,28 @@ def main():
     if rank == 0:
         print(f"[dispatch] OK (recv {recv_x.size(0)} tokens)", flush=True)
 
+    # XXX: forcing a device+group sync here is currently required for combine
+    # to see consistent dispatch outputs. Without this both send_nvl_head and
+    # the various *_channel_prefix_matrix tensors can still be in flight on
+    # the comm stream when combine launches, producing a deadlock inside the
+    # combine forwarder (NVL check never advances). Investigate proper
+    # stream-dependency hand-off in Buffer::internode_dispatch.
+    torch.cuda.synchronize()
+    dist.barrier(group=group)
+
     # internode_combine signature:
     # (x, topk_weights,
     #  src_meta, is_combined_token_in_rank,
     #  rdma_channel_prefix_matrix, rdma_rank_prefix_sum, gbl_channel_prefix_matrix,
     #  combined_rdma_head, combined_nvl_head, config, previous_event, async, allocate_on_comm_stream)
+    # NOTE: combine goes in the reverse direction of dispatch, so the prefix
+    # matrices passed here must be the RECEIVER-side ones returned by dispatch
+    # (`recv_rdma_channel_prefix_matrix`, `recv_rdma_rank_prefix_sum`,
+    # `recv_gbl_channel_prefix_matrix`) — not the sender-side ones.
     combined_x, combined_topk_weights, _ = buf.runtime.internode_combine(
         recv_x, recv_topk_weights,
         recv_src_meta, is_token_in_rank,
-        rdma_channel_prefix_matrix, recv_rdma_rank_prefix_sum, gbl_channel_prefix_matrix,
+        recv_rdma_channel_prefix_matrix, recv_rdma_rank_prefix_sum, recv_gbl_channel_prefix_matrix,
         send_rdma_head, send_nvl_head,
         cfg, None, False, False,
     )
@@ -182,8 +195,7 @@ def main():
     got = combined_x.float().mean(dim=1)
     diff = (got - expected).abs().max().item()
     max_exp = expected.abs().max().item()
-    if rank == 0:
-        print(f"[combine] max|got-expected|={diff:.4e} max|expected|={max_exp:.4e}", flush=True)
+    print(f"[combine r{rank}] max|got-expected|={diff:.4e} max|expected|={max_exp:.4e}", flush=True)
     assert diff < 1e-2, f"rank{rank}: combine mismatch max diff {diff}"
 
     dist.barrier(group=group)