Hello, canadianeh.
Thank you for using Apple Support Communities! If I understand correctly, when waking your MacBook Air from sleep, you are unable to use Touch ID. The only workaround you've found so far is to restart the Mac.
Use the following resource to help isolate the issue:
Isolating issues in Mac OS X - Apple Support
The support article linked above may lead you to reinstall macOS. I recommend creating a backup first, if you can.
Back up your Mac with Time Machine - Apple Support
Other ways to back up and restore files - Apple Support
I hope this helps! Take care.