You may notice the following error (or something similar) in the event viewer where BizTalk360 monitoring service is running.
BizTalk monitoring service fetches data from all the configured underlying BizTalk Environments to generate alerts. Configured BizTalk environments will be accessed using the service account configured for the monitoring service. So, it is mandatory to set up the service account for each BizTalk Administrators group.
For example, if you have configured 3 environments SIT, UAT and PROD in your premises, the service account must be a part of BizTalk Administrators group in all the environments.