Calc: Why can I not use both prefix-text and suffix-text in a user-defined format?

I can format a numeric field as “X” #.0
I can format a numeric field as #.0 “Z”

But I cannot format the field as “X” #.0 “Z”

With the latter format the field is always displayed with ###

This is with Calc


you can set a pre- and postfix, but the content to be displayed may become too wide for the cell.
see also: Error Codes in LibreOffice Calc

Solution: Set a larger column width using Format -> Columns -> Width ... (or just drag the column wider)

Hope that helps