Is Honor another Xiaomi/Redmi brand?
Have you followed all the steps in Android auto-fill including trying those for Xiaomi and Redmi?
Can anyone else confirm that Honor devices need some additional setup?
I have done a lot of research online today and can find no clues what to suggest for this brand of device. There seems to be very little information about them and only passing mentions of autofill functionality so I’m not sure where to look next. One would hope the lack of information indicates their devices work just like a stock Android device but your trouble getting this to work suggests that is not the case 
Is there a manufacturer support forum where you can ask for more information about what is needed to make Autofill work on their phones?