Q.Red tip photinia
I planted my Red tip photinia last spring and it hasn’t grown an inch. I mulched, watered accordingly, but no growth. Not dead, just isn’t growing. I was told this was a fast growing plant.
If there's no spotting on the leaves (which would indicate one of several diseases,) it sounds like the roots just need to be encouraged a bit. Plants will grow roots before they grow leaves. Follow the cultural recommendations for photinia that follow, (make sure there's enough sun,) and try increasing the phosphorous addition. https://www.gardeningknowhow.com/ornamental/shrubs/photinia/growing-red-tip-photinia.htm