When using Tools On Air Just:In software to generate a growing file in the new AVF format of AppleProRes, the file remains 5s long within Premiere while ingesting. The file never grows while the record is happening. As soon as the record finishes the file jumps to its proper length.
AVCi100 mxf files behave as expected, and the AVF ProRes files work as expected in Final Cut Pro as growing files.