If you create a custom format in SAS Studio 3.4 or 3.5, assign it as a permanent format to a variable in a DATA step, and then print the data set, the results are printed correctly. Although, if you change the custom format definition and then print the same data set, the updated format is not used. To circumvent the problem, use the format in a procedure step rather than permanently assigning it to the variable. That way, any changes to the format definition are reflected in the results in the same session.
We're working on a fix.