Why would rowbytes be negative and 4 times larger?

When receiving input and output worlds in Premiere (registered with pixel format of PrPixelFormat_BGRA_4444_32f), I keep getting the world that has the rowbytes equal to -30720 (for a typical 1920x1080 clip), while the new worlds, created using:

world_suiteP->PF_NewWorld(in_data->effect_ref, output->width, output->height, true, PF_PixelFormat_ARGB128, &moved_in));

Has the rowbytes equal to 7680, suggesting an 8-bit world, not 32-bit one. Interestingly, if I use PF_PixelFormat_BGRA32 the rowbytes value is the same.

Any thoughts on this discrepancy and suggestions on how to resolve it?