None of the Thule racks have a through bolt to lock the rack in place. Thule uses an expansion bolt to secure the rack into the receiver. The “finger” that goes into the receiver hole is an additional locking/safety feature.
I bought an Epos rack, which has a similar a mechanism, works very well and makes rack install and removal fast and easy. I’m dubious of OP’s claim that this information was buried in the manual. Even if this was true, not RTFM is foolhardy.