via CoindeskMalta-based OKEx is one of the more active cryptocurrency trading platforms. At issue, according to the company, is that one of its key holders has "been out of touch" while cooperating with a Beijing probe.CEO Jay Hao says the key holder's cooperation with Chinese officials is thanks to a "personal issue," and the investigation would not affect business.A Chinese news source says one of OKEx's founders "Star" Yu was detained by police at least a week ago, and hasn't been seen since.More from OKEx: "We are unable to disclose the nature of an ongoing investigation but would like to assure all OKEx users that their funds are safe and that all other functions on OKEx are unaffected."The news did send Bitcoin (BTC-USD) a bit lower, but it remains modestly higher for the day at $11.36K.The Grayscale Bitcoin Trust (GBTC) down 2% premarket.