No, I don’t think what you have described amounts to “gross misconduct”. However, if you have signed eg a daily check sheet stating that you checked the disc then I suppose they could look at it more seriously due to some degree of deliberate falsification of records (in their eyes).
I think you’ll be looking at some sort of reprimand/warning at worst.
Don’t forget - suspension as part of the disciplinary process is not a sanction - it is simply a way of removing you from the workplace while enquiries into the matter are made.
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