Migration Classic > OnSharepoint - only possible 1x per user ?

Hi everyone

I'm testing some behavious of the migration tool to see how I can help users in our org.

Specifically i'm testing to see how global Channels in Stream Classic are migrated to OnSharepoint and more specifically the bahaviour of embedded videos from those channels and other locations.

Im trying this on my own production user but I now ran into an issue.

It seems since my first initial migration, the migration tool now does not recognize any new uploaded videos to my Classic account. 

Is this a known issue or default behaviour ?