diff --git a/netbox_config_diff/configurator/base.py b/netbox_config_diff/configurator/base.py
index 0106ffe..5eda8ad 100644
--- a/netbox_config_diff/configurator/base.py
+++ b/netbox_config_diff/configurator/base.py
@@ -137,12 +137,15 @@ async def _collect_one_diff(self, device: ConfiguratorDeviceDataClass) -> None:
 
             device.diff = get_unified_diff(device.rendered_config, device.actual_config, device.name)
             self.logger.add_diff(device.name, diff=device.diff)
-            device.missing = diff_network_config(
-                device.rendered_config, device.actual_config, PLATFORM_MAPPING[device.platform]
-            )
-            device.extra = diff_network_config(
-                device.actual_config, device.rendered_config, PLATFORM_MAPPING[device.platform]
-            )
+            try:
+                device.missing = diff_network_config(
+                    device.rendered_config, device.actual_config, PLATFORM_MAPPING[device.platform]
+                )
+                device.extra = diff_network_config(
+                    device.actual_config, device.rendered_config, PLATFORM_MAPPING[device.platform]
+                )
+            except Exception as e:
+                self.logger.log_warning(f"Unable to get missing/extra commands for {device.name}: {e}")
             device.patch = get_remediation_commands(
                 device.name, device.platform, device.actual_config, device.rendered_config
             )
diff --git a/netbox_config_diff/configurator/platforms.py b/netbox_config_diff/configurator/platforms.py
index 45eb5a2..994faee 100644
--- a/netbox_config_diff/configurator/platforms.py
+++ b/netbox_config_diff/configurator/platforms.py
@@ -46,15 +46,15 @@ def _render_substituted_config(
 
         replace_sections = [(name, re.search(pattern=pattern, string=source_config)) for name, pattern in substitutes]
 
-        rendered_config = ""
+        rendered_config = config_template
         for name, replace_section in replace_sections:
             if not replace_section:
-                msg = f"substitution pattern {name} was unable to find a match in the target config" " source"
+                msg = f"substitution pattern {name} was unable to find a match in the target configsource"
                 self.logger.critical(msg)
                 raise TemplateError(msg)
 
             replace_group = replace_section.group()
-            rendered_config = config_template.replace(f"{{{{ {name} }}}}", replace_group)
+            rendered_config = rendered_config.replace(f"{{{{ {name} }}}}", replace_group)
 
         # remove any totally empty lines (from bad regex, or just device spitting out lines w/
         # nothing on it