Recently, I installed Windows 8.1 Pro on my MacBook Air (Early 2015, 13 inch).
Windows 8.1 worked fine for 2-3 days, but the drivers for trackpad and keyboard started to behave erratically and suddenly stopped working. I found out they weren't available in Control Panel. Bootcamp is upto date as well.
I tried to boot back into macOS but Boot Camp couldn't locate the macOS boot volume.
I restarted using the Alt key but my Mac booted from the Windows partition. Before, I used to hear a chime and see the Apple logo after startup, but now my Mac directly starts up in Windows.