New feature in Storyline 360: Interactive 360° images

I really like this new feature. I'm using it to show staff who've not been in our offices yet the inside of our meeting rooms. One query though - I've been using the panoramic picture tool on my smartphone and it's worked for most images. It always pops up the warning about the 2:1 ratio. But, I have a problem with one image. Storyline keeps flipping the image so it's upside down. A colleague said it might be related to the number of pixels. Is there a maximum pixel number that can be used for 360 images, or could it be something else?

Thanks