There doesn't seem to be a built-in way to catch events when attachments are being added via comments.
If an attachment was added via comments, it doesn't count as issue update or Attachments field change, so the respective triggers (issue update and field update) don't work.
We need a trigger for Attachment addition/removal. A possible solution would be to track the number of attachments in the Attachments field. If an attachment is added (via comment or directly to the field), then the count increases, working as a trigger.
I've tried different built-in workarounds but nothing worked. The only workable solution I found is having two automation rules:
1. One rule with a "field updated" trigger (Attachments field) and it works when attachment is directly added to the Attachments field.
2. Another rule with a "comment added" trigger and it checks if attachments exist or not using a condition block.
Having two duplicate automations with different triggers creates unnecessary workload. A simple trigger would eliminate such issues.
I couldn't add any suggestions for Atlassian Cloud, I guess they closed the inbox, so I'm starting the discussion here.
For context, we can't use any add-ons in my company and setting up web-hooks from other services to resolve this issue seems impractical.
Let me know your thoughts.