docs(transcodes): add dirty shutdown recovery to troubleshooting

Documents the known issue where an unclean shutdown leaves the --mount
bind-propagation entry in a broken state that prevents Emby from starting.
Recovery: remove mount → start → wait for load → re-add mount → restart.

Transcodes/Manual-Transcoding.md

@@ -462,6 +462,26 @@ readlink /mnt/ram-transcode
 # Existing sessions in progress are NEVER affected — only new sessions follow the flip.
 ```
 
+### Emby Won't Start After Dirty Shutdown
+
+After an unclean shutdown, the `--mount` bind-propagation entry in Extra Parameters can
+leave the container in a broken state where Emby refuses to start at all.
+
+```bash
+# Symptom: Emby fails to start with the --mount extra parameter present.
+# Cause: dirty shutdown left the bind mount in a state Docker can't recover.
+#
+# Recovery:
+# 1. Remove the --mount line from Emby Extra Parameters in unRAID Docker UI
+# 2. Start Emby and wait for it to fully load (check the WebUI is responsive)
+# 3. Add the --mount line back to Extra Parameters:
+#      --mount type=bind,source=/mnt/ram-transcode,target=/ext-ram-transcode,bind-propagation=shared
+# 4. Save changes and restart Emby
+#
+# The container starts cleanly without the mount, which clears the broken state.
+# Re-adding the mount after a clean start works reliably.
+```
+
 ### Increasing Ramdisk Size After Initial Setup
 
 ```bash