Still why wouldn't they open. They get quite a lot of sunlight in late morning. Think ithas been enough light for them to open.
I'm quite sure it was lavender and rosemary they talked about. Mine is a bit bare at the bottom and only three years old. Did try to strike cuttings last year but failed. Will try again. I thought the same was true for cotton lavender (not cutting into old woor) but saw that they cutt them back within an inch of its life at Kew and they sprouted back vigously.
But that doesn't explain why the flowers seems to just wilt away without opening at all. It seems like they cant open full stop.