Symptoms:
In the NSX-T Manager UI (not Policy) under: Security, Distributed firewall, General, you can set the Applied To as a logical switch for a Section.
If click Applied To and click Edit, in the Edit Section window which pops up, there are no Logical Switches displayed:
VMware NSX-T Data Center
This issue occurs due to incorrect API call in the backend.
This issue is resolved in NSX-T Data Center 3.1.3.
Workaround:
Currently there is no workaround.