When using replay in a "close to live" scenario, i.e.
JumpToNow and play, ReplayA (or B) randomly just stop/pause.

I would guess this has to do with latency in writing frames to disk making the playback reach last frame and thereby stopping playback even though it's not possible to go beyond live since we're playbacking at 100%.
Anyone knows if there is a way to work around this?

Using "Live-mode" is a no go since audio output for "live" is not for the live-frames instead for the frames playbacked on the timeline.