Hi,
I have checked your Custom CSS box of the Template Options and found out there was 6 times fontawesome was declared as font family which indicates fontawesome version 4.
https://prnt.sc/KkJrNyKfYkM-
Those are causing conflict with the recent update as our templates are now using fontawesome 5 free. So I have seached them and removed and all icons are appearing right now, even I have removed my code too that I have given you previously without checking your backend.
BTW, I have a suggestion for you, that I can see you have templates from both Helix3 and Helix Ultimate framework, which may cause conflicts as they are different in so many areas. Such as, module position, layout etc. So Please Keep templates from only one framework and remove the others, even you need to remove the system plugin of it too.
Kindly check and do let me know if everything is fine or not.
Best Regards