Out of the Box (Dx SaaS) .NET Agent does not support Restricted mode for .NET Core apps Engineering provided an early access ,NET core Agent v3 to address the issue.
Resolution
Given Early Access .NET Core Agent v3 Also set the below Agent filters on the IntroscopeAgent.profile
introscope.agent.dotnet.agentfilter.enabled=true introscope.agent.dotnet.agentfilter.pattern.excludes=AppPool Name introscope.agent.dotnet.agentfilter.pattern.includes=*.*