I am having the same issue with the fill-in-the-blank item (v2008.1.22).

A parameter of (s1) results in a single line box that will not allow for entry of characters beyond the size of that box. A parameter of (s1.5) or larger (I've tested s2, s3 as well) changes the size of the response box but the font size is smaller, the font colour is black instead of green, and an unlimited number of characters can be input into the response box. Additionally, with a parameter greater than (s1.5), the data for this item is stored in a text file and not the spss file. It seems that under these parameter conditions, the fill-in-the-blank item is being treated by ML as an essay item with a smaller response box.

Based on pilot testing using the essay item type, I need to be able to limit participant responses to one to two lines of text - incredibly participants want to respond with paragraphs of text. I have also unsuccessfully tried the parameter (s2, n255) to limit the characters that are allowed to be input but that string returns a single line text box and limits the characters to that single line of text.