Well, that sounds like a great question!!
Not a Catholic myself, but on that road, I think that maybe I can at least get a start on a decent answer.
Eucharist miracles - yes. Also, men like Padre Pio, and well others that have healed people, they didn’t always heal people wherever they were. Sometimes, lack of faith, sometimes for whatever reason.
Anyways, truly, a mark of Christ’s ministry was healing. That’s obvious by the following text:
Believe Me that I am in the Father, and the Father in Me; otherwise believe on account of the works themselves.
So, miracles are important. But not the crux of the issue, for a wicked and perverse generation desires a sign (Matthew 12:40).
Our faith should not hang on miracles or healings, or lack thereof. Well, you know that.
But, if indeed Christ is really there, then why don’t people always get healed if they’re sick and communicate (partake of the Eucharist)? I’d say that the healing is not the point. We benefit from the eucharist not primarily by the bread or wine we take, but by Christ. Why not get healed? Well, you are, don’t you receive Christ, don’t you get grace from a proper communion? Don’t you receive forgiveness of venial sins?
Also, it’s not like Christ is limited by the local presence of the Eucharist in healing people. Far from it, He can do things like that by through His priests and saints. In fact, as I understand it, that’s the more common historical “method” if you will. The eucharist is for certain purposes, communion with and partaking of Christ (and other purposes of course), but physical healing, that’s not a primary purpose of the Eucharist.
That’s way more beneficial than the physical aspect. But, yeah, sometimes people are healed physically.