Ryder here, from the Social Care Team at Shopify. Welcome to the Community and thanks for posting! Generally speaking, Google Chrome will be the most up to date browser and thus will operate more smoothly than other browsers. That being said, Safari on iPads and iPhones shouldn't have trouble loading your product images!
You mentioned that they can be seen on the main product page - did you mean they are displaying on the collection page, but upon clicking onto the product page the images have been disappearing? Can you provide your shop's link so I can try replicating the issue from my Safari browser?
If this ends up being an issue that requires further digging internally, we'll need to authenticate the account to gain access. In this case, you can get in touch with our Support Team through our Help Center page by logging in and selecting your shop. I hope this helps!