Two days later, they replied providing me a new session token for that deposit address:
afaik and happened to me once, they gave me voucher code instead
are you sure that's a session token and not a voucher code?
Considering that ChipMixer supposedly answered him saying that him (or someone else) sweeped the chips to an address, yes.
I dont think they are scamming. At the worst case, it was a bug or issue in their part. I may be biased, but they literally spent millions in their signature campaign, another shit ton of money in forum ads and already mixed hundreds of Bitcoins at once without exit scamming. Would they really scam someone for 0.17 BTC?