For the 16F1615 and 1619 you need MPASM 5.59 or higher.
I've got MPASMX v3.55 installed, it comes with v5.72 of the assembler and the assembler works fine with PBP3 as far as I can see. The Device Support document for IPE lists full support (program and debug) for the PICKit3 for both these devices.

Using MPLABX as the IDE for PBP might be a completely different story, I'm still hoping PBP3.1 will ship with proper support and documenation for that but I'm not feeling lucky.

/Henrik.