Do you check the logs?

Search for "Failed to connect" or "Connection failed" or "Authentication failed"

If you find something like that, paste here

Possibly try to update the nodes or the workflows which are not working. Have you tried to remove and add the same node? I don't know n8n much but it sounds as if you have some corrupted old version of them

When old workflows in n8n stop running after a previously working state, a common cause is:

🔁n8n version update or environment change affecting trigger nodes

• n8n has changed how workflows run—especially those with trigger nodes (like Gmail, Webhook, Cron, etc.).
• In recent versions, n8n won't auto-activate old workflows after restart unless:
  • The workflow is enabled, and
  • The trigger node is properly configured, and
  • No credentials have changed or become invalid.

🔍 Things to Check

1. Are workflows still marked as active?

• Go to the n8n dashboard → Workflows → Check if the old ones are enabled (green check).
• If not, re-enable manually.

2. Any credential/auth changes in Gmail or others?

• Go to Credentials tab.
• Reauthorize the Gmail credentials (OAuth tokens may expire or become invalid).
• Ensure Google API access is still granted and that scopes haven’t changed.

3. Check n8n logs

Run docker logs <container> or view process logs if self-hosted:

• Look for errors like:
  • Gmail trigger node failed to connect
  • Credential error
  • Cannot start workflow: Missing node parameters

4. Manual Execution stuck at "Fetching"

This usually means the trigger node is not emitting anything:

• For Gmail Trigger:
  • Ensure it’s configured to poll properly.
  • Check Gmail inbox has relevant new/unread emails (if using polling filter).
  • Try toggling the workflow off and on again.
• For Webhook Trigger:
  • Make sure the URL you're calling matches the new deployment endpoint if environment changed.

💡 Solutions

🔁 Recreate Trigger Nodes

• In affected workflows, delete and re-add the trigger node, especially if it’s a Gmail Trigger.
• This reinitializes it with updated node logic, which may have changed in recent versions.

🔐 Refresh Credentials

• Go to Credentials section → Open Gmail → Click "Reconnect" or reauthorize.

🛠 Update Environment

If you recently:

• Changed n8n version
• Moved to a different environment or container
• Updated Node.js version Then consider:
• Running a backup/export
• Fully recreating workflows or reimporting them (as some serialized nodes may fail silently)