%GetEmailV2Response.attachments% is a list of items. You need to either provide an index, or do a loop on it.
For example, using %GetEmailV2Response.attachments[0].id% will get you the Id of the first attachment. Or, if you do a For each loop on %GetEmailV2Response.attachments% then %CurrentItem.id% will give you the Id of the current attachment in each iteration of the loop.
-------------------------------------------------------------------------
If I have answered your question, please mark it as the preferred solution. If you like my response, please give it a Thumbs Up.
I also provide paid consultancy and development services using Power Automate. If you're interested, DM me and we can discuss it.
