Issues with grinding my own beans

I currently use a Delinghi Espresso machine and have always bought ready ground coffee because the cost of a decent grinder is quite high.
However for Christmas this year, quite a few people bought me coffee beans so I decided to buy myself (what I thought to be) a good budget grinder – Melitta Molino (Melitta seem to have a good name when it comes to coffee particularly when talking about filter coffee)

My question is… I have been using the Lavazza Espresso beans and generally grind about 10 cups worth at a time.
I notice that on the day of grinding the water basically runs straight through, there is next to no, dark syrup colour, it tends to start mid brown and within seconds looks clear.

the next day, however, I get a great coffee, nice dark syrup to begin which gets gradually lighter

I have used other beans which are generally darker, the lavazza Espresso beans are quite light in colour, I have not noticed this issue with other beans but I’m not sure if that is simply because they are more intense.

Should coffee brew better a day after grinding? does it let the ground beans dry out or something?
Or is it something that might be specific to these particular beans?

Or might there be something else that is causing the issue?