appsrc generating BYTES segments even with format set to TIME, causing crashes

I've been banging my head against this for several days, assuming I must be doing something wrong, but if I am, it's definitely not documented anywhere I can find. I've talked with slomo, the author of the Rust gstreamer bindings too, and he asserts that this should not be happening. I've set format=time in both receiving and sending threads, both before and after link and adding to a pipeline, I still get the same behavior. It seems to be defying the set_format call and sending BYTES segments anyways, which promptly crashes the program with a failed assertion.

Here is a GST_DEBUG=6 log of my attempts to understand what's going on.