As title:
fresh installed Avast, and FF estension missing. In previous FF builds, the extension was present and works well. It’s normal that it missing with that FF build? I’ve repaired and reinstalled Avast, but no extension in FF. The component is present in “components”. There’s something i can do or no more present in new FF builds? I have Firefox 59.0.2 64bit. Thanks.
It’s working on FF for me. I was once told that it could take up to 48 hrs. to show up after installation.
Almost 24 hours from installation, no extension yet. 
Hope is the last thing to fade. 
Repaired installation again, but nothing changes. The component is installed but not showing in FF. Is there anything else I can do besides waiting?
No.
Sure I had this problem a while ago,could be worth uninstalling Firefox and reinstall,think i got a popup box asking if i would like to allow online security.
could be wrong,but worth a try.
I had already tried before. No success. I will survive without it, too.
Edit:
repaired again and this time it works! Thanks to all.