Cannot go into streamable mode with mp4mux

Hello,

I am using mp4mux to get a mp4 stream with live data, so I set fragment-duration property and streamable property to TRUE. But the pipeline fails with following error:

GStreamer+qtmux: 0:02:31.996826505 0x7c7de6c280 ../gst/isomp4/gstqtmux.c:2369:gst_qt_mux_downstream_is_seekable: downstream did not handle seeking query GStreamer+qtmux: 0:02:31.996942338 0x7c7de6c280 ../gst/isomp4/gstqtmux.c:2992:gst_qt_mux_start_file: downstream is not seekable, but streamable=false. Will ignore that and create streamable output instead

It seems the streamable property cannot really be set to TRUE, it wants to force it but then the pipeline fails. That was working fine with older gstreamer versions, but doesn't seem to work now with 1.16.

Is there something specific to do to get it working ? Also I found it might be related to reported issue #362 (closed)

Thanks.