Okay, gonna say this just once: Stop posting in Bug Reports until you commit to using the template there. This was not anywhere near enough information for a bug report, and I'm also dead certain it's not a bug and that you did not take adequate steps to rule out a code problem first.

You mentioned that you're doing this via code. Per the documentation, winset uses parameter lists and those have special formatting. you can't simply throw the text directly in there and have it work.

When you use winset() to set the text for a label and you're not sure about what its contents may be (or you are sure, and know it contains characters like & and ; and " that can be an issue), you have to use list2params() or url_encode() to format it.

Alternatively, you can simply output() to a label.