Arrows not showing in output

Hi there.

I've come across a rather bizarre bug (I think) in Storyline 360. I've added a few arrows (shapes) to a layer, but they're not showing when previewing or in the exported output. Their default state is set to normal and there aren't any triggers attached to them.

I've done some testing and I can add a new arrow and it will show, unless I place it in a similar position to the other ones. For example, I can create a new arrow on the left side of the slide and it'll show, but if I create it near the other arrows it won't.

This will probably be clearer if you do some testing yourselves, so I've attached the slide in question. I had to remove all the content, as it contains business sensitive information, so it's all just placeholder text. The layer I'm referring to is 'Unit 1, Q1 Answer 1'.

In the proper Storyline file this bug is occurring on multiple layers, not just this one.

As I say, it seems like a bug, but thought I'd see if anyone could come up with a simple fix that doesn't involve me having to import the arrows as image files.

Thanks.