The world is not fully synced or has been corrupted

Error: The world is not fully synced or has been corrupted. Try playing the world on a console where it's in a good state and try migrating it again.

I began to receive this error shortly after our summer vacation and thought it had something to do with removing the XBox or some disruption to the local hard drive. However, after un-installing and re-installing the game multiple times as well as following an entire series of insane 'XBox help' options, nothing has worked. 

Not only is my main world corrupted, but also 'the copy of' prior to installing the additional lower layer is also corrupted. Most other worlds load fine, but most other worlds I don't particularly care about. (Other worlds are on average 100-500mb while my main save is 2.5 gb and its 'copy' is only 300mb)

I have two Xbox One Xs and I thought I might have accidentally switched them up so I did all of the same un-installing and re-installing on the other one to the same effect. I'm guessing the second XBox wasn't my primary one in the end either way (slightly different set-ups with them; one mainly for the kids)

I waited 25 minutes on my fibre-optic connection for my user profile to re-sync and still, my main save is corrupted. 

After attempting again on my second XBox (another 22 minute sync), I managed to load up a two-year old version of the game. I'm nervous this is simply going to have the effect of over-writing my actual save on 'the cloud.' 

Is there any possible fix or am I screwed?