If that is happening in v2.7.1, it is a bug. The shipping lines changes in v2.6, specifically the colonisation pressure mechanic, were designed to prevent that happening.
Can you confirm you have seen this behaviour in the latest version?
If that is happening in v2.7.1, it is a bug. The shipping lines changes in v2.6, specifically the colonisation pressure mechanic, were designed to prevent that happening.
Can you confirm you have seen this behaviour in the latest version?