I'm afraid it's not only due to the backlog. What happened was the following: I send ETH from Bitstamp to Bitshares through the OpenLedger gateway. The adress that Bitshares provided received the deposit but it was never credited to my account. I contacted OpenLedger, their support mentioned the backlog, they looked into it and then concluded it was specifically because I send it from Bitstamp and that there was nothing they could do. They included a link to an OpenLedger blogpost that warned about sending from Bitstamp. Obviously I hadn't read that blogpost beforehand and it was also not mentioned on the deposit page in Bitshares (which I think it should have).
Anyway, I just received an email from OpenLedger support that they will look into it again. Fingers crossed.