Ah, honestly speaking even I myself don't use manual on sites I play on because the connection on my end tend to be located far from the servers. It happened multiple times to me as well (and I suck at pulling out on Crash).

As you mentioned on using manual, we usually recommend utilizing the auto-cashout to avoid these kind of outcomes. By default, crash is a latency-sensitive game, so at times the response from the client (i.e. us players) might not register quick enough before the crash happens. Just like in a multiplayer games when we wonder why our actions take at least a second later to initiate. If you observe the top-left of the screen whenever a new round starts, a clickable dot is present to indicate the client's latency/ ping. From the image below, mine's terrible enough:



While I'm not from the Support team, do understand that the casino only takes responsibility if the issue falls on their servers or game providers. Using your case as an example, should the entire site encounter a sudden interruption right after you placed your bet, the casino will reimburse all affected players from that round. However since the client's latency is the issue, that falls outside of the casino's purview.