It seems I've hit some kind of limitation.
I was building a fairly big conversation with more than a thousand dialogue entries. And when I tried to link one entry to another conversation, just after clicking the "Another Conversation" option from the dropdown, I got this error:

It also happens in Outline Mode. And it doesn't happen with a small conversation.
So, searching a bit I've found this...:
https://issuetracker.unity3d.com/issues ... 00-scripts
I'm still in a fairly old DS version (can't happily update...), so I don't know if you've already modified DS according to that recommendation. If not, it would even be possible?
The thing is, if I need to stay under 1000 entries for each conversation, just to avoid this issue... that's going to hurt my workflow a bit...

Thanks.