We are having the same issue with Kaspersky Endpoint Security 10 SP2. If Kaspersky is active then Teams won't work. We've tried both temporarily disabling Kaspersky and adding a policy to allow MS Teams to not be blocked. We are using Application version 10.3.3.275 AES256.
Microsoft Teams blocked in Kaspersky Security Center 10
in Kaspersky Endpoint Security for Business
Posted