Port dimensions error out of nowhere

Hello,

so I've been using a .slx for a few weeks now, and today, without changing anything in the model, this error pops up:

Error in port widths or dimensions. 'Output Port 1' of 'Modell/Lageregelung/MATLAB Function' is a [3x3] matrix.

But the output is and has been a 3x1 vector.

Now if I insert a new Matlab function block with the following code

function FB = fcn(FL)
FB = FL;

which should just pass through the input, I get

Size mismatch (size [1 x 1] ~= size [3 x 1]).

For some reason Matlab expects FB to be 1x1, even though the size of FB is set to -1.

I have an older version of the .slx, and it works, even though I can't spot a difference anywhere.

I fixed the problem by setting the size of FB to 3 in the, but I would like to know what the issue is, since it cost me at least an hour of time.

[Jesús Zambrano]

If you include more details of what the Modell/Lageregelung/MATLAB Function is about and the screenshot of the model that function is placed, you might get help. Otherwise, it'll be difficult to detect the reason of that error message.