Here is NABU press release confirming that Artem Sytnyk was in DC from Jan 19-21 2016 on a "working visit"
nabu.gov.ua/en/novyny/nabu…
Biden led the effort to remove Shokin by threatening to withhold $1 billion in loan guarantees.
Following Shokin’s forced dismissal, the Burisma investigation was transferred to Sytnyk’s NABU, which then reportedly closed the investigation sometime in 2016.
According to the White House release, the two leaders agreed “to continue to move forward on Ukraine’s anti-corruption agenda.”