I am pretty concerned that I have lost some BTC.
For what it's worth: downtime has happened before, and ChipMixer always resolved everything. They're in the privacy business, they too want to remain anonymous, and I can imagine that makes updates in cases like this more difficult. Note that this is only speculation from my end, based on what I've seen so far.
That post was about the Bitcointalk user
ChipMixer not being online, it wasn't about the website itself.