LFS pointers broken after upgrade

I’m currently running new GitLab CE 11.0.1 inside of a Synology Docker container.

I’ve been trying to import repositories from an old GitLab CE 8 instance by importing all repositories via URL, however that didn’t seem to import LFS data.

I tried manually copying the shared/lfs-objects folder to the new instance, but LFS pointers still seem to be broken and all git lfs fetch commands return:

[9eac52f65ed675a441a5f006a074fdf5221340689993c8da0cd6bc671d14d811] Object does not exist on the server or you don't have permissions to access it: [404] Object does not exist on the server or you don't have permissions to access it

How do I properly import LFS objects? The only option I’ve found so far is by manually uploading new LFS data for every repository with git lfs push ...., but unfortunately I don’t have every project cloned on my disk.