I have a friend's KFL2019 and my Provari 2.5 can't see it. The 510 is too short (the Provari has an original KFL+ clone on top and I measured the 510 connections on both atties and the 2019 is a bit shorter)
Are you using the KFL2019 on a Provari?
I have two authentic KFL 2019s and I have a Provari Mini where the 510 pin did not make contact. To resolve it, I took the bottom insulator/insulator ring that goes on the center pin just underneath the build deck (like an inverted top hat), and with 300 grit sandpaper, I took off less than a mm from the wider flat end, which is now enough for my Provari to register it.