Can you please try this workaround and see if it is working or not. First see if arduino object can be created without using custom libraries.
Run the following command to see if this works fine:
a = arduino('COM3','Uno', 'TraceOn',true);
If this works fine, create arduino object with custom library and have trace on:
arduinoObj = arduino('COM3','Uno','Libraries','ExampleAddon/MQ3Uni','ForceBuild',true,'TraceOn',true);
This will give you debug information and upload errors of Arduino IDE at the MATLAB command window. There are some common possible causes of the error. Depending on what you see in your trace log, try the one that applies as follows:
