Don't know for sure what happened, they didn't even realize that their account was blocked by Instagram, Instagram might be stricter about gambling rules, that's why we rarely see casinos using Instagram as a social media that is used to promote
And they also don't have that reach on Instagram for most of the casinos so you usually see them posting there but best target audience available to them in on twitter so they focus more over there with lot of promotions constantly.I don't know if Instagram has strict rules for gambling but there are many advertisements going over there as well so depends on team whether they want to go for it or not.