我可以水平/垂直翻转图像，但我不能用GD2库旋转它们

I am developing a feature to allow an image to be rotated in increments of 90 degrees or to be flipped horizontally or vertically. I have the code working just fine on my own computer, but when uploaded to a live server, the rotate functionality stops working. The images can still be flipped, but rotating them results in no change at all. There are no error messages. The function that performs the rotation returns the same value as if the rotation was successful. This isn't a case of needing to reload the page (I've tried that). After rotating the image I should be able to find the image file on the server and find that it has indeed been rotated, but that is not happening.I am developing a feature to allow an image to