I've only had a single disconnect doing a contract so far, it's really weird how hit and miss this stuff seems with people.
They really need to get it in order for everyone though. At the very least an autosave the moment it happens.
Funnily enough, it's only during the main mission when I'm experimenting. Of course, this is because I am not speedrunning, worried about the constant "kick you off your seat" problem of disconnects. It feels somewhat saddening to know I am trying to play the game fast not for skill, but fear of being booted. The Featured Contracts are all quite short, so I've not had this issue, nor with the Prologue missions, which can take five minutes when I'm taking my time. If I'm trying to play the level in a "work with what you discover, not what you know" way of progression, I am more concerned of losing progress than even being
seen. Even the load times, which are balls awful, aren't a problem to me when compared to that.
What platform? I've seen a lot of people having constant issues on PS4, but on PC aside from the few hours after launch it seems mostly fine.
PS4. I was a sucker for the Sarajevo Six, back when I thought the game would launch with more than one mission for Paris. I would have gotten it on PC, but if I did I'd essentially need a new GPU. If I had the same problems there as I do here, I think I may lose control of the left side of my body. I know retrospect is usually highlights, but I've had more disconnects from this single player game than I did with GTA Online at launch. I find that awfully telling.