Hello Isuru_C
I checked it briefly on two different laptops and on both devices the website worked with different browsers without problems for me, which is why I suspect an individual device cause.
Sometimes it can cause problems if the device has a manual time setting instead of an automatic time setting. This setting may still be checked.
Of course, the QR code can also be activated from a mobile device, which does not matter for the activation and the presentation of the QR code during the journey.
We wish you a wonderful and unforgettable stay in Switzerland.
Kind regards,
Nicole