It keeps disconnecting
Why the same account gets signed out more than once, and the one change that actually stops it.
A session expiring once is normal. A session expiring on the same account, more than once, is not random and it is not something broken on BeReach's side. LinkedIn does this on purpose, and once you know the trigger it is easy to avoid.
The one cause
LinkedIn treats each login session as belonging to one place at a time. When you connect your account here, that session gets used by BeReach. If the same browser tab you connected from stays open and active on LinkedIn afterward, LinkedIn sees the same session being used from two places at once and shuts it down, on both ends. That is why your own browser gets signed out too when this happens.
What this does not mean
You do not need to stay off LinkedIn. LinkedIn is fine with several logins to the same account at once, that is what "log out of all devices" is for. The only login that conflicts is the exact one you connected from.
What to do
Close the tab you connected from
Right after pasting your session, close that browser tab (or sign out of it). It already did its job.
Keep browsing LinkedIn separately if you want to
Use a different browser profile, a private or incognito window, or a second device signed into the same account. Any of those is a separate login and will not conflict.
Reconnect
If the account already got signed out, paste a fresh session the same way you did the first time.
After you reconnect
Nothing is lost. Your chats, drafts, contacts, and history stay exactly where they were, and approved drafts pick up where they left off.