Can you change join to Inner?
Sorry, I've not provided enough info in my original post...
The join is an inner join and if I view/export the data it included the correct list I'm after. It seems the filter is being "clever" and just pulling all data from Table A before it performs the join on the data source.
Try this thing. Make a copy of the field which is returning you Null in filter. Drag it to Filter, Edit Filter, take out tick from NULL. Show this filter and also Hide card so that you dont see it in your list of filters.Now bring your original field in filter of which u just made a copy. Show Filter and from inverted Triangle on filter select only Relevant values.
The field itself doesn't return NULL. The filter is simply listing all values in Table A regardless of the INNER JOIN with Table B.
There must be something else in your join...It is difficult though to keep guessing...Looks Strange to me...Is there any field which is returning null and can be used
Thanks for continuing to try and help.
To try and explain a little better, when i view the data as a result of the data source join, it displays correctly and only returns the subset from table A, but when I add the same field as a filter, it shows everything.
I have created a calculated field that returns TRUE or FALSE. If this is true I want it to show in the users filter list. But when I try referencing my "Exists" column in the filter's condition it just tells me the field is invalid. I've included some screenshots in the hope it'll help show my problem.