I've had two counterphobic 6 coworkers.
The first, I believe, was an ENFJ 6w7 sx/so. When I met her, she was feisty and a workaholic, but very positive and a good role model. Sometimes she would have bad days where she was angry, but she also worked as assistant manager right into the end of her pregnancy, and she was still a faster and more reliable worker than basically anyone else in the department. She was very creative, fun, protective, strongwilled, and competitive. However, about a year later, she started coming to work angrier and angrier, and going on these huge paranoid rages. She made our boss into a scapegoat for all of the problems at our workplace. She tried a number of times to get him in trouble, and increasingly would leave the department to go talk to other people, and would do her work in the way that she "felt like doing it", instead of to company specs. It got to the point where people would dread sharing a shift with her because she made a mess of her station and ranted about the manager the whole time, and eventually chided us for not joining her crusade. It finally surfaced that she and her husband had privately broken up months ago, but were still living together until they could figure out the logistics of dividing childcare and separating their belongings. The timing of the breakup coincided almost perfectly with her downward spiral into "full retard", so to speak. The company didn't offer her a full-time position when she asked, despite her being a longtime employee, so she quit. She sort of got hit by the door on her way out... they surprised her by telling her to leave way before her standard two weeks were up. Honestly, I think everyone was just sick of her.
My other cp coworker was probably an ISTP 6w5 sp/sx. She was more your standard doomsday prepper type of 6. Very independent, fairly libertarian in values, and a doting grandmother. I loved the heck out of her. She was typically warm and funny, but a little paranoid, and hyperprotective of her possessions. She kept her things in a locked toolbox at work, and would flip completely if she discovered anything missing. One day she'd discovered her ice cream scoop had gone missing, and she yelled at our forgetful, disorganized manager (who had probably lost it) and she BEELINED to Target to buy her a new one. Another day we discovered someone took one of our department's brooms, and she walked right over to the new girl from another department who'd taken it (to be fair, she should not have taken it and was well aware of that when she did, and did not bother to bring it back), and yelled and cussed at her, lol. We equated her to a grizzly - warm and protective and good to have on your team, but really not fun to get on her bad side. Still, her bark was worse than her bite. She blissfully retired, and peaced out early of her own volition when the ENTJ head manager barked at her on her second-to-last day.
I think the key is in the reactivity. 6s respond when things happen. Unless they can pave their own way out via self-control and self-awareness, if things don't stop happening, the 6 doesn't stop reacting. 8s react too, but their impulse is to react by expressing their personal authority and taking control of the situation. 6's impulse is to try to prevent feeling unstable, so they keep reacting to the chain of changes, instead of just taking their own solid footing like an 8 would. So the 6 tends to be more ruled by the situation, and will struggle to recenter until their stressor dissipates. Hence the ENFJ 6 I know who got worse and worse as her relationship went downhill, but the ISTP 6 who was happy as a lark as soon as she'd locked her new scoop in her toolbox.
It's one of the reasons I appreciate my 9 so much... he seems to natively distance himself from the stressor. Sometimes for a 6 it can feel like you have no choice but to react. It's like you're blinded. It's been very helpful to me to watch someone else address stress by stepping back from it instead of feeling slave to it.
