I'm also starting to get no replies from the support. And my CLAMs are still in the limbo. I don't think any help can come if not from Poloniex itself, but they seem not to care much.
But maybe the experts here could provide some speculation on how it can happen that Poloniex got and provided us with a txid, but the transaction doesn't even appear on the explorer: That's a complete mystery to me!
I speculated earlier in this thread that the CLAM client's wallet could be corrupt in some way, so the client was occasionally generating transactions that appear to be good from Poloniex's side, but in reality are double spending. Such transactions will be immediately rejected by the network, and will never confirm.
After experiencing my own stuck withdrawal, I'm less inclined to think it's that, because the txid they provided at withdrawal time is the exact same transaction that made it to the network (eventually).
I wonder if it could be related to the problems that CLAM has with syncing from the network.
Frontend support is polite but effectively useless for more complicated issues. There doesn't seem to be any interest in discussing the problem, let alone fixing it. I reported a minor issue with the API and the reply basically just reiterated the problem without committing to a fix.
Thanks, that's informative. So at the root it might be an issue with the CLAM network, or, as one could infer from Poloniex reported answer on this Reddit post (