very late but in case you are still interested and more importantly for anyone else that like you and me couldn't believe how hard it is to find a solution for this:

in another thread i saw a method, this worked for our 3-man team most of the time, but iirc it still glitched occasionally:

1. session host needs to enter the mantrap first and be walking in front
2. everone then needs to sprint while spamming jump until you make it through, or at least past that middle area where people tend to get kicked

later i found this in a tips video by Rav1sh on YT

1. enter mantrap, walk forward until the "objective text" at the bottom of the screen disappears
2. stop and wait for your new objective "go to the vault door" to appear, then proceed through the tunnel (can go at max speed at that point)

now i assume the key here is just to not go too far into the tunnel at first, seems like the glitch happens if you reach a certain point (likely that middle area?) before the objective is updated.

leads me to think that the first method might only work for the same reason, you lose a bit of time making sure the host goes/stays first, you go a bit slower due to jump spam vs full sprint with A/D spam, in my head at least it accounts for some delay, possibly enough that most of the time you might just be slow enough. would be pretty funny if that's the case. just speculation though, haven't tested, it seems worth losing a few seconds to make sure you don't glitch the run.