Two similar Butler rules. One works. The other does not. Why?

Question

The working rule, behaves as expected, modified the state of the Checklist item that matches {triggercardlink}

when a card is moved out of list "COMPLETED 📤" by anyone,
for each card linked in the attachments, 
uncheck item "{triggercardlink}", 
and post comment "Card {triggercardlink} marked incomplete on {date} by {username}."

The resisting rule, that does not behave as expected...

when someone is added to a card, 
for each card linked in the attachments, 
uncheck item "{triggercardlink}", 
and assign the item to member @{matchedusername}

The non-working rule throws the error:

Wednesday, January 26, 2022 4:34 PMRunning command on board Hemhah.

This action requires a trigger or prior action related to a checklist item.

The first, working rule doesn't have this requirement. Any ideas?

Hannah Humbert - Simpla Workflows · Answer

Hey @Robert le Grange ! Sorry for the late reply. Here's what it looks like for me:

Robert le Grange · Answer

Thanks for the attention and the suggestion @Hannah Humbert - Simpla Workflows

Tried your idea; but nothing changed. Odd, I am CoNFuSeD.

To describe what I want to achieve is the following:

I create a Parent card, add a Checklist, any Items added to the Checklist are turned into linked Child cards, which include an Attachment of the Parent card. This part works fine.

What I want to achieve is automatically updating the Items in Checklist on the Parent card, when there are changes in the Child card, like: Adding a Member, or setting a Due date. This is the part that I can't get right.

Hannah Humbert - Simpla Workflows · Answer

Hey @Robert le Grange ! Welcome to the community :)  try replacing {matchedusername} with {username}. I'm guessing it's throwing the error because it's expecting the trigger to have something to do with a checklist item member.