New machine - no throughput

Hello all,

I bought a Delonghi Primadonna Class ECAM 550.65MS in January 2021.
After 4 months of average use and a 4 person household then unfortunately no more coffee came out of the coffee spout. Pump ran but on.
As a little background. I have bought when new machine extra, in addition to Delonghi's supplied, a water hardness test strip. Since we buy extra a spring water that is made for coffee machines was recommended to me with both strips a hardness of 1. Consequently, the machine has not shown any descaling in 4 months, which surprised me a bit. Nevertheless, I cleaned it daily in the accessible places and washed the brewing unit. I do not use a water filter.
Since it is now a very young machine I went to Saturn, who in turn sent the machine to the manufacturer.
After initially receiving an estimate for a complete cleaning, Delonghi decided to replace the calcified hose and clean the calcified machine as a gesture of goodwill. The final statement from Delonghi was: Setting hardness level 1 is completely unrealistic and all water has a lime content.
I then set it to hardness level 4 just to be on the safe side.
A month later, last Friday, I decalcified the machine myself for the first time.
Now to my problem. Since the machine has been at the manufacturer's, I get a message every second time I switch it on that there is no water in the circuit and often no water comes through the coffee spout when I switch it on. The coffee comes out normally and tastes fine.
Can anyone answer me where this can come from and whether this is bad?
Thanks for your help.