Check this topic – https://www.8theme.com/topic/unknown-theme-content-error/
I do not see this error on your site – https://prnt.sc/1x6avf0 , provide a link, please.
Filters work fine – https://prnt.sc/1x6awwk Could you record a video of the problem?
One standard license is valid only for 1 project. Running multiple projects on a single license is a copyright violation.