Hi @diysarah,
A warm welcome to the Bunnings Workshop community, it is fantastic to have you with us.
The problem is to do with drainage. Those decorative pots don't appear to have any drainage holes, which means any water poured on the soil is sitting at the bottom of the pot with nowhere to go.
Repotting them in nursery pots, which have drainage holes built in, is the right move, but sitting them back inside the decorative pot negates that drainage to some degree.
If you add some drainage gravel to the bottom of the decorative pot before setting your nursery pot inside it, you will create a reservoir at the bottom of the pot that the water can sit in. The roots can then wick water from this reservoir when they need it. Without this reservoir, the water will sit in the soil, slowly rotting the roots.
Alternatively, you can repot them in a self-watering pot or a pot with drainage holes and a saucer.
To help your plants recover, remove them from their pots and check the roots. Trim away anything black, mushy, or foul-smelling, then repot into fresh, free-draining mix with plenty of perlite and orchid bark. Avoid reusing the old, mouldy soil.
After repotting, water sparingly and allow the soil to dry out more thoroughly between waterings. Place the plants in bright, indirect light and maintain humidity for the Grey Star.
Unfortunately, the reality is, when root rot has set in, it may be too late, and they can't be saved.
If you have your receipt and they are less than 12 months old, our Perfect Plant Promise means you can return them for a replacement. See the Returns section on our website for further details.
Let me know if you have any further questions.
Jacob
