Problem running standalone app

I am writing a code to read files from two different instruments and trying to turn into an app (using MacOS). It works fine in matlab (2021a) but does not work in the standalone app. Can anybody help with this? Here is the code. Thank you.

function plotButtonPushed(app, event)

fileK = app.EditField.Value % K spectrum

[~,~,ext] = fileparts(which(fileK)); % detemine file extension

if strcmp(ext,'.txt')

dataK = load(fileK);

livetimeK = dataK(1,2);

else strcmp(ext,'.cnf')

[dataK realtimeK livetimeK] = readCNFv1(app, fileK); % to read cnf files

end

end