Custom size URL problem/bug

This is cross posted in the API forum because I'm really not sure whether this is an API issue or a custom size image URL issue.

Some users of my slideshow are now having a problem with the display of some images in their slideshows. When I've tracked down the issue, it's because a customURL in an API response doesn't work when I try to change the custom size.

Here's a request:

GET /services/api/json/1.3.0/?method=smugmug.images.get&APIKey=m3fjH1x4QjX6N10RsaVUeWr0dgg2oQoZ&AlbumID=19280882&AlbumKey=FjQhcH&Heavy=true&CustomSize=195x127&Extras=Origin&rnd=1317886192534 HTTP/1.1

Here's a piece of the response:

{
            "id": 1411675121,
            "Key": "bH9Bcmv",
            "Album": {
                "id": 18332267,
                "Key": "7qQ77p",
                "URL": "http://www.brisk-photography.com/Clients/Laura-C/18332267_7qQ77p#1411675121_bH9Bcmv"
            },
            "Caption": "",
            "CustomURL": "http://www.brisk-photography.com/Clients/Laura-C/i-bH9Bcmv/0/uJbfV6DlrMh3YAtkh9lNVvKZMyM%3D-1317886841-195x127/Laura-118-195x127.jpg",
            "FileName": "Laura-118.jpg",
            "Format": "JPG",
            "Height": 4032,
            "Keywords": "Laura, model, portrait, Laura, 118",
            "LargeURL": "http://www.brisk-photography.com/Clients/Laura-C/i-bH9Bcmv/0/BBFp%2B74n9xho0qANXWOLttuYvSU%3D-1317886841-L/Laura-118-L.jpg",
            "LastUpdated": "2011-08-01 18:35:47",
            "LightboxURL": "http://www.brisk-photography.com/Other/Homepage-Slideshow/19280882_FjQhcH#1411675121_bH9Bcmv-A-LB",
            "MediumURL": "http://www.brisk-photography.com/Clients/Laura-C/i-bH9Bcmv/0/KbC0psxZC%2AHwuDcvrp2gRY4Qi0Y%3D-1317886841-M/Laura-118-M.jpg",
            "OriginalURL": "http://www.brisk-photography.com/Clients/Laura-C/i-bH9Bcmv/0/fQ8h7viYpD%2BKfPEm5hIMK7ERlo8%3D-1317886841-O/Laura-118.jpg",
            "Position": 1,
            "Serial": 0,
            "Size": 3286263,
            "SmallURL": "http://www.brisk-photography.com/Clients/Laura-C/i-bH9Bcmv/0/4aHzMjgIsHGOpAN415qPGOVQtTA%3D-1317886841-S/Laura-118-S.jpg",
            "ThumbURL": "http://www.brisk-photography.com/Clients/Laura-C/i-bH9Bcmv/0/8Q4FTqoZRQ3VvnYXTDAqnJScCs8%3D-1317886841-Th/Laura-118-Th.jpg",
            "TinyURL": "http://www.brisk-photography.com/Clients/Laura-C/i-bH9Bcmv/0/%2B2EI96PGPIb8hZ2315aw6roSQYo%3D-1317886841-Ti/Laura-118-Ti.jpg",
            "Type": "Collected",
            "URL": "http://www.brisk-photography.com/Other/Homepage-Slideshow/19280882_FjQhcH#1411675121_bH9Bcmv",
            "Width": 3024,
            "X2LargeURL": "http://www.brisk-photography.com/Clients/Laura-C/i-bH9Bcmv/0/RvQrpuFxkUltSEUKukhAXFb9wvw%3D-1317886841-X2/Laura-118-X2.jpg",
            "X3LargeURL": "http://www.brisk-photography.com/Clients/Laura-C/i-bH9Bcmv/0/%2BDGwYaUkZ8I9k2wXqFpKmO%2B89rM%3D-1317886841-X3/Laura-118-X3.jpg",
            "XLargeURL": "http://www.brisk-photography.com/Clients/Laura-C/i-bH9Bcmv/0/0eMBOLmlTj2ma2UvWMKUZ9Ux0XM%3D-1317886841-XL/Laura-118-XL.jpg"
        }

The customURL from the API response is this:

http://www.brisk-photography.com/Clients/Laura-C/i-bH9Bcmv/0/uJbfV6DlrMh3YAtkh9lNVvKZMyM%3D-1317886841-195x127/Laura-118-195x127.jpg

By itself, it works.

But, per your advice, to generate a different custom size, I take that URL and simply change the custom size in the two places that it appears. But, no matter how I change it, the URL stops working. For example, if I change it to this:

http://www.brisk-photography.com/Clients/Laura-C/i-bH9Bcmv/0/uJbfV6DlrMh3YAtkh9lNVvKZMyM%3D-1317886841-1159x1139/Laura-118-1159x1139.jpg

The URL no longer works. It returns a blank gif image and the viewer gets an empty slide in the slideshow. This problem appears to be fairly new. It was not noticed until a few weeks ago. I've got a couple reports of it so far.

For reference, the gallery is this: http://www.brisk-photography.com/Other/Homepage-Slideshow/19280882_FjQhcH.

And, the image I referenced above in the gallery is this: http://www.brisk-photography.com/Other/Homepage-Slideshow/19280882_FjQhcH#1411675121_bH9Bcmv

Please help figure out why custom size images aren't working reliably. The more I look into this, I'm not sure whether this is an API issue or a custom size generation issue. If it's not an API issue, please help bring this to the attention of the appropriate developer. There are multiple slideshows that are showing blank images because of this issue so I'd like to figure out how to resolve it.

I should add that this issue only occurs on some images in the gallery.