Dear @Jean_Pierre_Traets , thanks for the reference - this will be helpful!
I’m still unable to understand why the formula went wrong though.
The formula chip shows that my Project Type reference is of another format. But it follows the same
“structure” as the company type.
Essentially, when you compare side by side, both “Company Type” and “Project Type” are looking up information from a column in another table that is essentially, just a text column
The “problem” might not come from your [Project Type] lookup field but from your Projects field.
Your Projects field is the one outputting a list of rows from your Projects table (I guess ) in the first place (as this what the visual cue for thisRow.Projects is indicating).
So, in your formula thisRow.Projects.[Projects Type], [Project Type] outputs a list of lists of rows from your table [Project Type].
Here’s a screenshot of what I get when gathering Projects within a multi-select lookup field by manually selecting only 1 project per row and then try to get the related type of the selected project in another multi-select lookup field