If it has been an issue since early 2018, then it isn't a mistake. It is easy to sit there and collect monthly payments while customers go at it between support lines that are pointing fingers at each other.
My advice, if they have been charging money for a service that won't deliver what you are paying for, then demand a refund for your monthly payments. If it means contacting your CC company or bringing this up with your state's attorney general.
I've been following this thread for a bit and I'm in the same boat. I first noticed the Facebook disconnect about six months ago. I kind of let it go, but when I would add any new products they wouldn't migrate over to Instagram. So I found this thread (and many more) and followed a lot of the instruction.
Multiple people said "delete Facebook off Shopify," but I would NOT delete your Facebook apps from Shopify. When I deleted the Facebook apps I lost ALL the product tagging on Instagram. Like, years. I also did the "delete integrations" over on the Facebook business page. When the Facebook apps were downloaded again, I only got like ten items (out of many) to migrate over to Instagram and then it's just been a headache ever since. My main issue is I just want the product tags on Instagram, but I can't seem to get that far because parent host, Facebook, won't connect.
I think we are at the point where we have to raise hell until it hits them where it hurts - the bank. Until they start losing money, they will leave the issue as it is. As of right now they can sit comfortably because of their buyout of Oberlo. Nothing else works as seamlessly. That said, they cannot expect to charge us 30 a month with a major ongoing issue. Lets be real, facebook knows the world and as such they are the best bet at driving traffic to your store. This feature needs to ducking work.