I'm not familiar with the particular Species 'Jane', but know that Magnolias have (like all spring bloomers) very short bloom times. Pair that with some windy and wild weather, and that is how long the flowers last. Many of my neighbors have Mags, and all have lost their blooms during the high winds weather we had lately in SE WI.

I planted an equally small tree at patio edge, called Tamarix, (which is a nasty wild shrub/tree in western states) but it is tall, whispy, and oh, so lovely in my SE
WI yard. It has magenta (teeny) florets nearly all summer.
Very few trees have that attribute. Next, I will try a smoke bush, I think.
Pondy

Thanks. I've been noticing around town that all the magnolias are losing their flowers. I think ours lost it's flowers so soon because it is so small. But it is getting a second batch of flowers on it, meaning it went bare and is coming into bloom for the second time.