Struggling with Allium — would appreciate advice

I want to be honest: I'm not getting great results with Allium and I'm not entirely sure why. blindness with no flowers produced from weak or immature bulbs has been a recurring problem despite my attempts to address it. I've been focusing on adding grit to the planting hole in heavy clay soils based on everything I've read.

wide range of flower forms, heights, and flowering times is there in glimpses, which tells me the plant has potential in my conditions. I have it in a mixed border with later-emerging perennials to hide dying foliage which might not be ideal. planting new bulbs in autumn for next year's display showed some improvement. Two stars for now — not the plant's fault, but not a success yet. I'll update if things improve.