What's wrong with this Promeneae Xanthina?

[vadam22]

I'd need some help with my mum's P. Xanthina. New growth appeared few month ago and now the top of the new leaves started to go brown and dry.

Could anyone help to identify what's wrong or?

[Ray]

What temperature range is the plant getting?

[vadam22]

It was outside until the night temperate dropped to 10C°. Then it was taken inside where it is around 22-18 C°.

[Roberta]

The plant looks rather dehydrated to me. I suggest taking it out of the pot and checking the roots - if the roots are bad it can't take up water.

I grow this species outdoors all the time, and night temperatures can get down to 2-3 deg C or occasionally lower (but it has acclimated to my growing situation) ... I think your temperature range is not a problem.