Hi, Steve.
A very common cause of this problem is having an icon that does not include multiple sizes (16x16, 32x32, etc) in one file.
This KnowledgeBase discusses that as it pertains to LabVIEW, but it applies to CVI as well. (Pay particular attention to the third paragraph in the solution.)
Let me know if that doesn't fix the problem. Have a nice evening.
Sarah K.
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