The only reason sats would go missing is if the other party force closes the channel.. and the fees are too high for the channel to close. It will close eventually. The channel must “clear” on-chain in order for the funds to be retrieved. 

Personally, I have been running a note for three years and I have never had someone force close a channel on me. And I make sure to open my channels with higher fees so that in case they close.  (either on purpose or on accident.) then my channel can still clear on chain.