Many Pulse issues arise from not configuring the communication between Pulse and TM1 correctly i.e. either the TM1 credentials are entered incorrectly in Pulse, the password has changed and is no longer valid, or the TM1 account does not have the TM1 “Admin” privileges required by Pulse.
I have a Feature Request with Development to add a “Test Credentials” button to the Instance Settings page, but a good workaround is to invoke the “Administration | Update Documentation” function on a suspect TM1 instance. The documentation update process needs valid TM1 “Admin” credentials to run, and will report a failure otherwise.