We have noticed in a survey via web form that, while the upload widget says images are restricted to <10MB, trying to upload something between 9.5MB and 10MB will cause an error after hitting the submit button. "Failed to Submit - cannot add attachment". I thought maybe the image size was increasing a bit during the upload, but when I checked older submissions and re-downloaded the attachments, the file sizes were the same as the original uploads. Maybe there is still a temporary file size increase during the upload process? I was able to submit an image of 9.45MB in size successfully, but multiple images between 9.5 and 10MB all resulted in that same error.
Anyone else run into this yet? While it's not a huge issue and we can add a note that says <9.5MB, we can't change what the actual widget says, so it could be a little confusing for users who happen to catch it.
I think the issue you are seeing is MB (megabytes, base 10) vs MiB (mebibyte, base 2) - 9.5 MiB is 9.96 MB. Which OS are you seeing this in?
I believe it was through the web form (Chrome, Windows 10 64bit). Sorry I didn't see your reply earlier.