Why does fit() not find heuristic starting points for exp1 models?

Hi,

I am running Matlab 2019a and I am stuck with a problem I cant quite wrap my head around. I want to use the following code to create an exponential fit based on the code CFTool creats:

%% Fit: 'untitled fit 1'.
[xData, yData] = prepareCurveData( [], test );

% Set up fittype and options.
ft = fittype( 'exp1' );
opts = fitoptions( 'Method', 'NonlinearLeastSquares' );
opts.Display = 'Off';
opts.Normalize = 'on';
opts.StartPoint = [];

% Fit model to data.
[fitresult, gof] = fit( xData, yData, ft, opts );

However, when I run it, I get the following error and it fails to fit meaningfully:

Warning: NaN, Inf, or complex value detected in startpoint;

choosing random starting point instead.

> In curvefit.attention.Warning/throw (line 30)

In fit>iFit (line 307)

In fit (line 116)

I dont understand why that happens as the documentation lists exponential models as having optimized starting points. Can someone point me to the mistake? Am I missing something? CFTool can define starting points just fine but it doesnt work in the code for some reason. Also if I switch to exp2, it works without a hitch but I need to fit a bunch of exp1 in a row and cant do it manually.