Azelea leads dying

Hi all,

Have two potted azaleas and one of them is really struggling

Soil is correct and fresh.
Had a problem which looked like scorch and lace bug which is now treated and cut back several branches and removed all dying leaves. New growth came but is starting to show same effects

Leaves turning black at edges then shrivel until most of leaves goes brown.

Watering and nutrients are fine as the second pot is fine.

See two pics I've attached, any ideas?