One of the other things that hasn't been metioned is the use of ferrules with the weildmuller connectors. We used them on nearly all of our competition robot connections and have had zero issues.
Here is the
white paper from Weildmuller recommending their use with stranded wires.
We import ours from China using Aliexpress but you can also get them from US electronics vendors, ebay, or Amazon.
Make sure you are using the right crimp tool and gauge ferrules. Also get 8mm long ones.