Are you using DSM 7.0.1 OR Are you using DSM 7.1 Beta/RC ?
DSM 7.1 Beta/RC has problems. I am working with Synology to resolve before DSM launches , if possible.
I will also need more information about your DSM 6 → DSM 7 migration.
That task does take a very long time to complete for some users (2 weeks for one user).
Anything you can detail (screenshots or whatever) helps.
Breaking it down for me (line by line if need be) helps.
I’m trying to create the mental image of what you have