Impossible to connect dashboard field filter to only 1 question

I have a dashboard with many questions (~15), most of them done through the Metabase editor, and a few through SQL.
I have created two dashboard field filters that I want to link to all questions. It works for all of them except one, for which it says : "Column to filter on: No valid fields".

I don't understand why, since I can go in this question and create the exact same filter, and it works.
I have converted it in SQL with SQL filters, and I can link them too. (I can't keep it this way as it won't update in the future since this question is based on other saved questions)

What am I missing?

Hi @KevM
Post "Diagnostic Info" from Admin > Troubleshooting.
The type of variable widget used in the question is very important to which dashboard filters you can use.

I don't have admin permissions, I will ask an admin to retrieve this :+1:

The filters I have on my dashboard are "Text or Category" > "Dropdown" filters. Then again, the card I can't connect is not a SQL question but one created purely through the Metabase builder.
I have a simple visualisation in the end like that:

@KevM I'm guessing that you have a Custom Column after the aggregation: - upvote by clicking :+1: on the first post

That's exactly it, thanks!
Good to hear it is a design flaw