For sure there are many reasons why OP still wants to play on those online casinos, even though as you said that they aren't well-known platforms. Based on my own experience, one of the reason why I still play on casinos that aren't even trusted is because of the promotions they offered like free spin without any deposits requirements. But even so, it is of course best to avoid these kinds of sites as much as possible for also to avoid this kind of problem, even if they offer good promo.
Then what is a point/advantage of those promotional free things if one can't utilize or withdraw those winnings. It will be just waste of time and effort so good to avoid those low profile or less known platforms. Its always good to play which have high ratings and positive reviews to avoid these kind of problem and offer nice support system if any problem occurs.