A venture started by WeWork Inc. and Rhone Group defaulted on a loan for a San Francisco office tower, Bloomberg News reported. The $240 million loan was for a building at 600 California St. that is owned by funds managed by a venture formed by WeWork and Rhone in 2019 to buy and oversee real estate. The property, which includes a WeWork coworking space as an anchor tenant, is located in San Francisco’s Financial District. Office property defaults are starting to pile up as landlords including Pacific Investment Management Co.’s Columbia Property Trust grapple with the pressure from rising rates and seek to kickstart negotations with lenders. Markets such as San Francisco have been under particular strain as technology companies slash jobs and pull back on their office space.