I believe that it was deliberately delayed until now to provide ammunition to support the California Democratic Party's endorsement of Kevin De Leon for U.S. Senator, even though Feinstein trounced him by better than a 3-1 margin (2.9 million votes vs. 804,000 votes for De Leon) in the June Primary.
This affair demonstrates that even the votes of registered Democrats don't count, unless they mesh with the wishes of the puppet masters who pull the strings.
Driving Miss Dianne: Senator Feinstein employed Chinese spy for 20 years
RT | Aug 3, 2018
When told that her driver of 20 years was a spy for China, Senator Dianne Feinstein (D-California) was reportedly 'mortified.' The staffer was fired and the whole thing quietly swept under the rug - until now.
Buried deep in a recent Politico story about alleged Russian spying in Silicon Valley was the revelation that a long-time staffer at Feinstein's California office had been passing information to Chinese intelligence.