i migrated a site from j1.5 to 3 and had issues that stumped everyone. Spent 10 hours until i found ACL Manager. The program instantly fixed 95% of my problems and then their Excellent support fixed all my other problems. The support people went above and beyond to help me.
If you have migration issues, stop wasting time and get ACL manager. That is what I did and I am soooo happy I did