Questions about 'Dash trickplay(trick mode)'

Hi
I am adding a 3x3 jpeg image thumbnail to Dash.

If I set the thumbnail interval with 'duration' in the mpd file as shown below, everything works normally.

<AdaptationSet id="2" contentType="image">
<SegmentTemplate timescale="100" duration="9000" media="$RepresentationID$-$Number$.jpg" startNumber="1">
</SegmentTemplate>
<Representation id="Image-2-0-320x240-3x3-20240416_180029" bandwidth="2000000" width="960" height="720" mimeType="image/jpeg">
<EssentialProperty schemeIdUri="http://dashif.org/guidelines/thumbnail_tile" value="3x3"/>
</Representation>
</AdaptationSet>

But the problem is as follows:
in the same situation
I set it to SegmentTimeLine as shown below

<AdaptationSet id="2" contentType="image">
<SegmentTemplate timescale="100" media="$RepresentationID$-$Number$.jpg" startNumber="1">
<SegmentTimeline>
<S t="0" d="9000" r="4"/>
</SegmentTimeline>
</SegmentTemplate>
<Representation id="Image-2-0-320x240-3x3-20240416_172842" bandwidth="2000000" width="960" height="720" mimeType="image/jpeg">
<EssentialProperty schemeIdUri="http://dashif.org/guidelines/thumbnail_tile" value="3x3"/>
</Representation>
</AdaptationSet>

When playing on a Roku stick,
Play starts from the time of the thumbnail right before the thumbnail playback time I want. (In the case of duration, it is played in the normal position.)

The interval between each thumbnail is 10sec.

What is the problem?