NSX-T roubleshooting Guide, checking the nsxa or nsx-mpa status and logs could be helpful, is there specific errors that provide more detail:
Check the Transport Node Status
Make the following API call to get the state of the transport node.
If the call returns the error RPC timeout, perform the following troubleshooting steps:
If the call returns the error partial_success, there are many possible causes. Start by looking at the nsxa logs. On the ESXi host, check hostd.log and vmkernel.log. On KVM, syslogholds all the logs.