Preview stopped working - or rather is no longer visible

Hi

I have not used Storyline for a while but needed to update a resource today and find the 'preview' function not working properly.

It seems to go through the process as the progress bar shows, but then it shows just a blank slide with the usual 'close preview' etc buttons visible but no content.

I was on update 8, so have installed 10 but the issue persists.

Is anyone able to advise a solution to this?

Many thanks!