I gues they returned the old script for migration in official documentation that always had issues (cased by the fact that sqlite and mysql schemas are not 100% the same).
Thare are 2 ways you can fiy your problem:
- Make a fresh instalation of Mysql seafile and compare database schema and manually fix (you need to have SQL command knowledge) yours so that it will match with fresh one
- Migrate again using a longer procedure with alternative script i wrote here (you need to scroll down for updated download link), it was not tested on 7.1.x so no guarantees.
Migate from SQLite to MySQL - script for 6+ versions - Seafile Server - Seafile Community Forum