Unable to set up a jump server.

服务器需要用跳板机进行连接，但是在已经添加了连接到跳板机的session的情况下，新建session并选择代理方式为跳板机后，跳板无任何可选的选项。

Reproduce the reported flow: create a session to a jump server, then create another session and select the jump-server proxy option. Inspect the proxy/session-selection entry point to determine why the existing jump-server session is not offered; done means an available jump-server choice appears and the new session connects through it.

Written by the indexing model from the issue text.