Migrated videos still in Stream (Classic)

As far as I'm aware, the issues with the Migration tool were resolved, yes. Some things to look into ...

You're saying that those 10 remaining visible were definitely migrated, right? Because if you had a filter set to migrate only certain videos based on criteria like number of views or published after a certain date, then maybe those 10 remaining visible were in fact not migrated because they were filtered out. (That is normal behavior, for the channel to display what was not migrated.)

Check your inventory report to make sure that those 10 visible weren't perhaps ones that were ineligible for migration, or duplicated videos. In the Msoft documentation, they give a detailed description of an order of operations on a single video to determine where it ends up. So you can have what looks like a Companywide or Group Channel that displays 20 videos, but 10 of them were uploaded by someone to their own personal channel first, and they shared it into the group channel. Those 10 would go to that person's OneDrive whenever you migrate their personal channel, but they are still going to show up in the Companywide\Group channel until you have migrated their personal channel.

Then it gets extra confusing if the end-user did an upload twice ... same video can APPEAR in two places but only stored in one (described above). But also, they could have simply uploaded the video twice so that it is DUPLICATED and stored in two places.

Running a full inventory report after your migration might help you figure out what's going on.

IsEligibleForMigration will tell you if any of those 10 were not eligible for reasons like not published, error state, or deleted.

MigratedDestination will tell you line by line what video migrated where. See if the 10 you're looking at have values in this column.

ContainerVideosInClassicUI will tell you how many videos were appearing to the end-users when they viewed the channel. For your described probablem, it may say 270, but if you filter the report for that particular container, your filter may only give you 260.

If none of that helps and it does seem like your mysterious 10 videos should have been migrated, were in fact migrated, and have not been hidden from Stream (Classic), then you should probably open a ticket for support. April 15 is approaching fast for everyone!