Clojurians Log v2

I'm learning to work with cognitect/transcriptor and I'm getting unexpected behavior using it in the repl: https://clojurians.slack.com/files/U0E9KE222/FA6D9ATA4/-.clj

If I evaluate it form by form, or as a region, the check! expression returns nil, as expected. But if I send the buffer, I get