This post was closed as off-topic. If possible I'd like to discuss it being reopened or at least have a better understanding of its closure so I can rework it or avoid future mis-postings.
I understand that the checkpoint is being taken by hyper-V, but as I say in the post, production checkpoints directly interact with the guest os, Ubunutu in this case, and it is only when the guest os is active, and on this vm specifically, vs other ubuntu vms that are having no trouble, that I can't get a production checkpoint to work, to me this all points to this specific install of ubuntu having a problem that is preventing the checkpoint from being created, which seems on topic since the problem and subsequent fix is presumably inside the Ubunutu guest.
This is all very separate from traditional checkpoints which do not interact with the guest os and which I am having absolutely no problems with.
Thank you for your time.