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.