[Satellite6.1] getting a subscription details takes too long or even does not terminate

Issue

Below actions take many minutes or even dont terminate at all:

• clicking to a subscription details in WebUI (URL like https://satelltie.example.com/subscriptions/2/info)
• getting list of content hosts attached to a particular subscription
• possibly some another request related to (details of) one subscription

The problem is not tightened to specific subscription but happens to any one.