diff --git a/src/runtime2/consensus.rs b/src/runtime2/consensus.rs
index 8e5e985f91578aa95625780c1bd0b1d30e83042a..b9980cbe237784ea95c05c76c986e651322ba3b3 100644
--- a/src/runtime2/consensus.rs
+++ b/src/runtime2/consensus.rs
@@ -350,7 +350,10 @@ impl Consensus {
         // TODO: Handle multiple firings. Right now we just assign the current
         //  branch to the `None` value because we know we can only send once.
         let data_header = DataHeader{
-            expected_mapping: branch.channel_mapping.clone(),
+            expected_mapping: branch.channel_mapping.iter()
+                .filter(|v| v.registered_id.is_some() || v.channel_id == port_info.channel_id)
+                .copied()
+                .collect(),
             sending_port: port_info.self_id,
             target_port: port_info.peer_id,
             new_mapping: branch.cur_marker,
diff --git a/src/runtime2/mod.rs b/src/runtime2/mod.rs
index bb039dbccc97e7707b8108ff31d0b73c5527b785..333f3e860354847eacb74b10880d7ff759dd1e82 100644
--- a/src/runtime2/mod.rs
+++ b/src/runtime2/mod.rs
@@ -431,7 +431,7 @@ impl ConnectorStore {
             }
         }
 
-        println!("DEBUG [ global store  ] Created component at {}", key.index);
+        // println!("DEBUG [ global store  ] Created component at {}", key.index);
         return key;
     }
 
@@ -444,7 +444,7 @@ impl ConnectorStore {
             // Note: but not deallocating!
         }
 
-        println!("DEBUG [ global store  ] Destroyed component at {}", key.index);
+        // println!("DEBUG [ global store  ] Destroyed component at {}", key.index);
         self.free.push(key.index as usize);
     }
 }
diff --git a/src/runtime2/scheduler.rs b/src/runtime2/scheduler.rs
index 3bc9c94477458743706ed7f8c32e622a41ef3bd6..14ebc566d0fa252649a9a9a71c91a29a432aad7b 100644
--- a/src/runtime2/scheduler.rs
+++ b/src/runtime2/scheduler.rs
@@ -208,7 +208,7 @@ impl Scheduler {
         // Note: we're not handling the public inbox, we're dealing with the
         // private one!
         debug_assert!(scheduled.shutting_down);
-        while let Some(message) = scheduled.ctx.read_next_message() {
+        while let Some(message) = scheduled.ctx.read_next_message_even_if_not_in_sync() {
             let target_port_and_round_number = match &message {
                 Message::Data(msg) => Some((msg.data_header.target_port, msg.sync_header.sync_round)),
                 Message::SyncComp(_) => None,
@@ -405,11 +405,11 @@ impl Scheduler {
 
     // TODO: Remove, this is debugging stuff
     fn debug(&self, message: &str) {
-        println!("DEBUG [thrd:{:02} conn:  ]: {}", self.scheduler_id, message);
+        // println!("DEBUG [thrd:{:02} conn:  ]: {}", self.scheduler_id, message);
     }
 
     fn debug_conn(&self, conn: ConnectorId, message: &str) {
-        println!("DEBUG [thrd:{:02} conn:{:02}]: {}", self.scheduler_id, conn.0, message);
+        // println!("DEBUG [thrd:{:02} conn:{:02}]: {}", self.scheduler_id, conn.0, message);
     }
 }
 
@@ -579,6 +579,10 @@ impl ComponentCtx {
     // TODO: Fix the clone of the data message, entirely unnecessary
     pub(crate) fn read_next_message(&mut self) -> Option<Message> {
         if !self.is_in_sync { return None; }
+        return self.read_next_message_even_if_not_in_sync();
+    }
+
+    pub(crate) fn read_next_message_even_if_not_in_sync(&mut self) -> Option<Message> {
         if self.inbox_len_read == self.inbox_messages.len() { return None; }
 
         // We want to keep data messages in the inbox, because we need to check
diff --git a/src/runtime2/tests/mod.rs b/src/runtime2/tests/mod.rs
index 29c6c9621e87b27bf8a198a446a90a16aa477171..be4f43c5f300a707b8ea07ac8f7b2cac72ed69c4 100644
--- a/src/runtime2/tests/mod.rs
+++ b/src/runtime2/tests/mod.rs
@@ -16,8 +16,8 @@ use crate::runtime2::native::{ApplicationSyncAction};
 // pub(crate) const NUM_LOOPS: u32 = 8;       // number of loops within a single test (not used by all tests)
 
 pub(crate) const NUM_THREADS: u32 = 1;
-pub(crate) const NUM_INSTANCES: u32 = 1;
-pub(crate) const NUM_LOOPS: u32 = 1;
+pub(crate) const NUM_INSTANCES: u32 = 5;
+pub(crate) const NUM_LOOPS: u32 = 5;
 
 
 fn create_runtime(pdl: &str) -> Runtime {
diff --git a/src/runtime2/tests/sync_failure.rs b/src/runtime2/tests/sync_failure.rs
index 392b8a22fa18fbf5c6fe934059189f7bfd84bea9..f3acdabcf1fbbd962ce73e7fe41de47edde701db 100644
--- a/src/runtime2/tests/sync_failure.rs
+++ b/src/runtime2/tests/sync_failure.rs
@@ -36,7 +36,9 @@ fn test_local_sync_failure() {
 #[test]
 fn test_shared_sync_failure() {
     // Same as above. One of the components should fail, the other should follow
-    // suit because it cannot complete a sync round.
+    // suit because it cannot complete a sync round. We intentionally have an
+    // infinite loop in the while condition because we need at least two loops
+    // for the last error to get picked up.
     const CODE: &'static str = "
     enum Location { BeforeSync, AfterPut, AfterGet, AfterSync, Never }
     primitive failing_at_location(in<bool> input, out<bool> output, Location loc) {
@@ -63,7 +65,7 @@ fn test_shared_sync_failure() {
     ";
 
     run_test_in_runtime(CODE, |api| {
-        for variant in 0..1 {
+        for variant in 0..4 { // all `Location` enum variants, except `Never`.
             // Create the channels
             api.create_connector("", "constructor", ValueGroup::new_stack(vec![
                 Value::Enum(variant)