@Jennifer_Dungan 

I'm currently facing the same issue, if you solved it, could you please share the solution or the reason behind it? 

Dear Community,   Can you please help with troubleshooting ECID? We have some websites (domain and subdomains) with the same setup in Adobe Launch for Adobe analytics and ECID. But one of the subdomains doesn't get ECID resolved, and therefore FID is used by AA.   The AMCV and s_fid cookies ar...