We have a website with 8 languages.
Translations are already added in Spanish.
French translators clicks the green link symbol to join sentences. When he does this, the Spanish translations get the status 'needs updating'. The added Spanish translations are gone for the fields that the French translator joined.
This is currently expected, as the Advanced Translation Editor saved the translations per segment inside Translation Memory.
Once segments are joined, they will need to get translated again.
The sense of joining segments is to make automatic translation work better in case a sentence has too many segments and the automatic translation does not work as expected in terms of grammar or sense.