How to get Outlook 365 <--> Bigin to sync two ways

Hi, I'm testing Bigin and the integration with Office 365. If I create a contact in Bigin, it shows up almost immediately in my Outlook contacts with a category "Bigin Contacts - [org ID]."

However, it's not working in the other direction. When I add a contact in Outlook and add this category tag, it does not appear in Bigin. The help article states that each should sync with the other:

"Integrating your Microsoft 365 and Bigin accounts allows you to synchronize contacts and events from Bigin to Microsoft 365 and vice versa. This ensures that whenever a Contact or an Event is added in one account, it will be updated in the other automatically."

Any advice on how to get this working?

It would be great if Bigin had an Outlook add-in side panel to access functions from within Outlook (as Zoho CRM appears to have). But absent that, getting this sync working is pretty important to avoid lots of manual entry.

Thanks!