(1) no need for framed here (now you get funny margins) \framed is just for testing here. Without \framed is there a same problem.
(2) factor is fit uses the current hsize and available vertical space, and since you don't use a par after midaligned, the available space is not calculated as you expect; (tex only updates pagetotal/goal after a par I tested it with \par after \midaligned, I got the same error. My problem is: TeX floats a low picture to a new page and puts a pagebreak after that picture.
normally the factor=fit is used in combination with \placefigure Some pictures are wider then the pagewidth, I used both factor=fit and factor=max, and I got everytime the correct size.
The threecolumn layout works just without \placefigure. I posted an example, please, look it closer. Greetings Bence