Bypass EOP anti-spam filter in a hybrid implementation

Hi,

I have a exchange hybrid and a third-party antispam solution. My messages are coming from this antispam go to my exchange onprem and then go to Exchange online. I configured a transport rule to bypass anti-spam in Office 365 (changing SCL to -1), however some messages are identified as SPAM by Office 365. 

I followed this article: https://docs.microsoft.com/en-us/microsoft-365/security/office-365-security/use-mail-flow-rules-to-set-the-spam-confidence-level-scl-in-messages?view=o365-worldwide

but anti-spam aren't being skipped. What can be wrong?

Thanks!