Hi @Roger_Dupuis , beyond the useful links posted here above by @arco , I made some time ago a detailed post about different scenarios about pick-up editing, in case you forgot to create a pick-up, using different insert mode scopes. Maybe it can be of some help:
EDIT: sorry, I have noticed that you use Dorico3.5, so maybe you don’t have insert mode scopes, which where probably added later in Dorico?.