Hello @amac,
This is the same issue that I also noticed a couple of days ago.
Approach
I was trying to implement adding/updating multiple images to the attachment field based on the list data process.
The problem was I had a list of things that go through the loop which calls an API and updates the image to the Attachment field.
At the end that attachment field has multiple images are there.
Problem
Then I found that the attachment field replaces everything when I update the attachment field using the Automation script block within that loop. In the end, only one image is there because it replaces all the previous attached data from the attachment field when requested for an update.
How I solved it.
Just use my own tricks like on that loop every time get the last updated image URLs merge it with the new image URL and update it. Using this approach just update the attachment field multiple times but in the end, I get what I need.
Note: My implementation for these all things is done using Automation Script Block within that Repeat Step.
Why this is hard to directly implement on Airtable?
Let's see and check the approach of Make, It's a native platform for automation & integration.
As Airtable automation Repeat, they also have an Iterator. Which do the same things in their capacity and supported modules.
But they support another type of concept which is called Aggregators, Which helps to combine data that we've processed during Repeatation(Iteration). They support Text, Array and JSON.
Make has those capabilities because the platform itself specializes in the purpose of automation.
But here on Airtable, there are lots of different things like Data, Automation, Interface and Forms.
Initially, there were Data parts only and later Airtable added these different parts match to the competition and don't rely on third-party tools.
I don't think Airtable are adding these Aggregators related to the same things because the usage of automation steps will be increased and ultimately they need to process more things. Also, remember that Airtable counts full automation as a single automation run. On the other end, Make is charged as per Operation based.
My Recommendations
First, try the trick that I've applied.
I recommend you to use Internal Automation when there is basic logic is applied. Also, try to use Automation Script Block which itself has more capabilities for custom calculation and data formation.
If it's beyond that internal automation and script then use Make.
I hope you understand my concerns 👍
