Be advised, for some it has gone for a few minutes, for others it has required a few days.
The process of converting your metadata (however much you have) is a one-time “pain” you must endure if you wish to keep all your customizations and history.
Don’t worry if DSM logs you out.
you have multiple ways of watching progress and determining when complete.
Plex/Migration.log – It will log each step, and signal completion
Resource Monitor will show find, realpath, or 'mv running.
LET IT RUN to completion.
If you interrupt, you’ll split the data and make a mess. I can put it back together but it takes a LOT of effort.
