AirDrop

My iPhone7 plus can not find the other PC for AirDrop like used be...

I have an iMac and MacBook Air and iPhone find iMac only...

The MacBook Air can find the iPhone...

Now I can not send my pictures, movies so on to MacBook Air which I need to...

I'm wondering that if I need to update a software to MacBook that is making this trouble???

If anyone know and give the answer, I really appreciate it. Thanks.