Yes, there are some common issues with Office 365 migration but they are usually straightforward to fix if you know what to expect. I myself had problems such as poor migration pace, login authorization failures and sometimes incomplete synchronization of mailbox data. For majority of these problems, I utilized Softaken Office 365 to Office 365 Migration Tool and the tool is quite stable and easy to use. When the migration slows down, I typically decrease the load or run it in batches. Fix for permission issues check for admin access before starting. Carefully selecting every folder can avoid missing data. What I enjoy the most is how the tool organizes everything and there's no confusion during transfer. It made troubleshooting much easier for me and the whole process was easy and hassle free.