Hello Jaime,
So, I managed to reproduce the same situation.
Reversing Migration postings will not retire fixed asset. You will need to maintain deactivation date.
As per your screenshot (And also with my testing), I noticed that Deactivation date is grayed out which means we will not be able to set the deactivation date.
To Enable this,
1) remove the process control entry set up for the migration.
2) Close the migration Project
Now Deactivation date should be enabled. Set the date to retire asset.
3) Create new Project in business configuration for migration
4) redo Migration with Correct data
Anantharaman Lekshmi : Thanks for the help and clarification.
Cheers.
Harshal