I know little about 11sp, but I don't think it's much different to any of the Ergo family, it just has more teeth on the ratchets.
If the problem was on the rear mech, I'd have said the G Springs in the Ergo are worn, but I've not heard of the same problem with a front mech. I've stripped down a few right-hand Ergos, both 9sp and 10sp, so I'm well versed in their internals. The left-hand control may be exactly the same except it's a mirror image of course.
So I reckon, and it's only a guess, that the Ergo G Springs are worn.
Hopefully someone will come on here with a better idea, but this forum is VERY quiet these days.