They all have good LFS, good water, 60-85% humidity. Our climate is tropical (summer now) with temperatures very close to what D adelae would get in its natural range. Over the past two months I tried more light for some plants, less light for some, with no noticeable difference. Obviously they can't catch insects without dew, so I tried 'feeding' tiny drops of very dilute liquid fertiliser (similar to your Maxsea). It didn't damage the leaves and it seemed to encourage some new leaf growth. But still no dew. All the plants continue to look poorly and one of them is seriously miserable (RHS in photo).
Any ideas on what's wrong? How can I help them recover?