We have come to the conclusion that images larger than 1MB cannot be uploaded from the iOS app.
We can send screenshots and any image less than 1MB, but when the image is larger, it gets stuck as “uploading 1 element” as you can see in the attached file.
We also tried to change the format of the photos on the iPhone from HEIF to JPG, but the problem persists.
From web, everything works very Well!