While I've never encountered a problem with Watchtower, I think I just found one. For many years I've had a patient portal account with a local health and hospital venue and their IT department is fully managed by cernerhealth.com. I recently setup another patient portal with an additional health and hospital system also managed by cernerhealth.com. While they provide different login URLs for each health venues, they DEMAND using the same login credentials.
I have two separate Login items in 1Password, both using the same username and password. Yet Watchtower doesn't flag these in "Reused Passwords". Shouldn't it?
1Password Version: 1Password 7 Version 7.6 (70600005) 1Password Store
Extension Version: 7.6
OS Version: 10.15.6
Sync Type: 1Password