Cercis Avondale advice

I planted a small cercis Avondale in my garden about 5 years ago and it has flowered in spring each year followed by leaves and grown really well. Last spring it didn’t flower or develop any leaves, scraped back a couple of the branches and all appears to be well underneath so I left it alone. Does anyone have any advice about what could be causing the issue? There’s no growth or sign of anything happening again this year. It’s such a lovely pretty little tree! It’s planted in half sun/half shade and the soil is ‘new build’ quality and quite clay heavy but I did dig a lot of compost in before planting.