I see in the migration guide it mentions be at version 6.4.4 but never says anything about 6.4.5. Does anyone know if migrating from nsx 6.4.5 is supported?
My guess would be that it just wasn't tested with 6.4.5. Might work, but no guarantees.
Maybe, but:
NSX-v 6.4.5 was released in April, 2019.
NSX-T 2.4 was released in February, 2019.
That might be a problem because the migration coordinator wasn't aware of NSX-v 6.4.5 when it was released. So maybe it will work, but it could also be possible that the migration coordinator stops during the pre-checks for the configuration import process.
NSX-T 2.4.1 was released in May which has a new migration coordinator but the guide hasn't been updated since April.