Matlab Online listbox handles issue

Hi,

I have coded a GUI which runs properly on my desktop Matlab R2019b. I am trying to execute the same GUI on Matlab Online, however it fails due to a Reference to non-existent field 'listbox1'.

GUIDE Inspector shows the Listbox properties with a correct Tag.

The error message on Matlab Online Command Window is below:

Reference to non-existent field 'listbox1'.

Error in SegmentationTool>processListUpdate (line 375)

set(handles.listbox1,'string',text_m,'Fontsize',8,'Value',idx)

Error in SegmentationTool>pb_add_process_Callback (line 268)

processListUpdate(handles)

Error in gui_mainfcn (line 95)

feval(varargin{:});

Error in SegmentationTool (line 42)

gui_mainfcn(gui_State, varargin{:});

Error in matlab.graphics.internal.figfile.FigFile/read>@(hObject,eventdata)SegmentationTool('pb_add_process_Callback',hObject,eventdata,guidata(hObject))

Error while evaluating UIControl Callback.

A breakpoint right before the error shows that the listbox1 is not in the handles struct, neither in the GUI.

Q1. Are listboxes supported in Matlab Online?

Q2. If yes, how or where could I found/manage them?

Thanks in advance.