You can only see the payload contents when you know the secrets.
The online LoRaWAN packet decoder will only show the public parts (it also accepts Hex). As this does not know the secret keys, that online version can only show the public data. But the great library from https://github.com/anthonykirby/lora-packet can also validate the MIC and decode the payload if you provide the secrets.
(The online version was working a minute ago, but is showing Error: Cannot find module 'lora-packet@0.6.0' right now. This has happened before and will resolve itself…)