Matlab Custom Add-On disappearing from Add-On list after restarting the Matlab instant

Hi,

I am working with custom Matlab add-on (simulink toolbox) which I tried installing (with/without admin access), but everytime I close the Matlab and reopen the new instance I lose that add-on from add-on list that also mean I am not able to use those custom toolboxes.

Please note I still see the custom add-on installation present on the disk at following folder.

Users\<user.name>\AppData\Roaming\MathWorks\MATLAB Add-Ons\Toolboxes\<<CustomToolBox>>

Does anyone know what is the resolution to this?