I kind of had a similar experience, I tried adding an IMS precision basket to my gaggia to get better shots, but found them still unreliable and inconsistent.

Ultimately it was the machine that was the cause, a better machine and the issue went away.

Agree, this feels a bit like yelling at the wind.

This particular grinder clearly isn’t doing time based dosing any longer for a reason that eludes the obvious troubleshooting.

Single dosing is an easy fix, and the most obvious one this side of swapping for another grinder.

I’m going to go against the trend here and say soy. We get one here called happy happy soy boy and it’s excellent for milk coffee.

I personally prefer the taste of soy in coffee to oat, I find oat slightly too thin.

Almond is the worst, I believe there’s a technical explanation for this, something about the oils, but I can’t recall the details.

Anyway I recommend finding a high quality soy and giving that a go.