As this could be helpful for somebody in a similar position I was in, here's another update.
I don't have an exact date, but around the beginning of December finally the first four spots in the suggested tab started to be awarded again to my channel videos. So I'd say it took to Youtube algorithm between 4-5 months to gather enough data to bring my channel viewership back to what it was before leaving Fullscreen.
It's worth nothing that I did not have monetized my channel before joining Fullscreen.
So if you have Adsense enabled before entering a network, once the contract expires and you reconnect the channel to your personal Adsense it might be possible that you won't experience this "limbo" period as the system may have still stored your previous Adsense performances (again, just a guess on my part that could be completely wrong
).