Viburnum turning brown

[u/onsay101]

So 1 of the 5 Viburnum I planted a few months back has been on a slow roll turning brown. Just got back from a 10 day Holliday to find it completely gone. Has plenty of rain while we were away. Search suggests sunburn but then why are the others ok? Shot with the tree in the background is facing north so I don’t think the tree is giving that much shade to the others to make such a stark difference.

[u/onsay101]

Forgot to mention, northern Sydney area.