I've seen situations where a node appears to be doing nothing but in fact was still busy indexing data because there were lots of secondary indexes defined against the tables. After the streams have finished, the receiving node also needs to finish compaction before it completely joins the cluster. I would recommend that you monitor the last few tasks/operations in the debug.log to get a good sense of what is going on.
It looks like when you resumed the bootstrap, it kicked off a "duplicate" round of streams because the initial one hasn't completed. I've never done that before myself so I don't have any experience with a "dual bootstrap" situation. Cheers!
