It's certainly not an A typical situation where a professor does not provide clear instructions or even changes instructions from what was conveyed to a student at an earlier time. A student being, say, charged with an academic misconduct violation for failing to follow those instructions, you have to bear in mind, was the professor say within his obligations or expectations to provide the clear instructions? Was it truly the student's fault? Did the professor actually change the instructions where there should be no culpability on the students for it? It is very case and fact-specific.
What you do need to understand is you cannot depend on the professor or the school or the conduct office to be doing the right thing or to have an understanding of the circumstances. Before you engage with the school in any capacity, you need to take the necessary precautions. Having an experienced academic misconduct attorney advisor will be your best ally. They can help you understand and navigate the process and they should be involved from as early as possible in an academic misconduct case.