I never had an issue with them, and as you can see above, I've played a fair bunch at Deloro and made some big withdrawals, which were always instant.
In my entire gambling "career" I never encountered a Casino which didn't pay; the worst cases were delayed payments.
Neither did I ever meet someone in all those years who ran into any issues besides delayed payments, unless they breached the T&C or didn't provide the required documents. (I exclude those people, that play on shady (crypto)casinos, that aren't listed anywhere, lol)
Just do a rough probability calculation >
example:
Casino is listed on AG, listed in the top 20, is certified (results in a LOT of traffic for 'em)
Casino has a weekly withdrawal traffic of lets say, a mere 30 people
Casino has 10 complaints per year (including unreported cases)
30x52 = 1560 withdrawals
10 / 1560 = 0.6% of players encountered a problem, which either got resolved or was not resolved
and furthermore, if you look closely at the reports, in plenty of cases it's the user's fault > wrong documents, didn't understand T&C (especially bonus T&C) etc.