Only some images are not loading in gallery?

Hi there!

I have a PowerApp that pulls from a SharePoint list that has an image field. 

In the app, I have a gallery that pulls the image, the title, and the description for each item. each item has a .PNG icon as the image if that is helpful. 

70% of the items are pulling in perfectly. About 30% are not pulling in the image at all. It seems that maybe the larger images are struggling more, but that rule doesn't seem consistent, and I do not see any guidance anywhere about what the size limit might be (if there is one and that is indeed the problem?)

Any thoughts appreciated!