diff --git a/libs/ardour/vst3_plugin.cc b/libs/ardour/vst3_plugin.cc
index a97cf5cbbc..2e885f1947 100644
--- a/libs/ardour/vst3_plugin.cc
+++ b/libs/ardour/vst3_plugin.cc
@@ -866,8 +866,6 @@ VST3Plugin::connect_and_run (BufferSet&  bufs,
 		}
 	}
 
-	//_plug->enable_io (_connected_inputs, _connected_outputs); // XXX
-
 	_plug->process (ins, outs, n_samples);
 
 	/* handle outgoing MIDI events */
@@ -1334,6 +1332,7 @@ VST3PI::VST3PI (std::shared_ptr<ARDOUR::VST3PluginModule> m, std::string unique_
 	query_io_config ();
 
 	if (n_audio_inputs () == 0 && n_audio_outputs () == 0 && n_midi_inputs () == 0 && n_midi_outputs () == 0) {
+		DEBUG_TRACE (DEBUG::VST3Config, "forcing I/O rescan with stereo layout\n");
 		/* see also vst3_scan discover_vst3 -- assume stereo by default */
 		request_bus_layout (2, 0, 2);
 		query_io_config ();
@@ -2387,11 +2386,11 @@ VST3PI::enable_io (std::vector<bool> const& ins, std::vector<bool> const& outs,
 	_enabled_audio_in  = ins;
 	_enabled_audio_out = outs;
 
-	//assert (_enabled_audio_in.size () == n_audio_inputs ());
-	//assert (_enabled_audio_out.size () == n_audio_outputs ());
 	/* check that settings have not changed */
 	assert (_n_bus_in == _component->getBusCount (Vst::kAudio, Vst::kInput));
 	assert (_n_bus_out == _component->getBusCount (Vst::kAudio, Vst::kOutput));
+	assert (_bus_info_in.size () == _n_bus_in);
+	assert (_bus_info_out.size () == _n_bus_out);
 
 	DEBUG_TRACE (DEBUG::VST3Config, string_compose ("VST3PI::enable_io: n_bus_in = %1 n_bus_out = %2\n", _n_bus_in, _n_bus_out));