Published Video crashing after 10 seconds

Hi all
I'm hoping you can help.
On Storyline360, I'm publishing a video, with just 1 slide afterwards.
The video is not that large, 77,551kb.

On Storyline preview, everything works perfectly, however when publishing both to Review360 and to LMS, the video pauses after approx 10 seconds and all functions, such as replay, stop working, so it has basically crashed.

I have left all quality options as optimised for standard delivery.
I am on version V3.60.26947.0 and no updates are showing on my Articulate dashboard.

Any advice please?

Many thanks
Chris