Problema com Whatsapp web Sophos UTM 9

Good afternoon,

I have a Sophos UTM 9 System with several Social Network filters and group of sectors.

User is connected to a wired network, and uses the social network Whatsapp WEB ... I have a problem sending media via the WEB, by cell phone he normally sends the media, but via Whatsapp WEB he keeps loading but does not send ... I adopted a free access policy where there is no restriction and it worked normally but I cannot leave this policy to users because if I have no problems on the Network. I've already analyzed the filter in every possible way and I can't find where the Whatsapp Web block is ... I look forward to returning,

Thanks.