Because I still don't have my daily mixes, I contacted support again.
The guy didn't have a clue about the ticket sent to R&D that his colleagued previously said he opened.
Instead, he gave me this weird explanation: my account has been part of a trial concerning the daily mixes, Weirdly, this trial doesn't cover Premium services, so when I switch to Premium, they dissapear (weirdly, they need to regenerate it seems, when you switch to Premium). He told me to wait another month. I've waited for more than 2 weeks already and I'm really sure things will not solve in the future. However, I will contact support again next month until they acknowledge it's a bug and ask development to make a fix.
I have another friend who created a new free account, after some days already got 4 daily mixes, then switched to Premium a week ago. Since then, no daily mix. For me it's obvious, it's a general bug, linked not only to my account, but to multiple accounts. If this happened where I work, I would probably do extra hours to solve the problem. But the support guy said my friend has been part of the same trial. Weirdly, he said that without asking me what is my friend's username.
I will not dwell on other obvious bugs, like Discover Weekly not being under Discover tab, its shortcut not working on my phone screen, the fact that on the free subscription I saw things like reccommended playlists based on other playlists or on multiple artists, features which don't show up on the Premium account, the fact that I actually have a daily mix on Premium, it's just that it's stuck and never gets updated..
Good thing they add me free days to my Premium account, so at least I haven't paid to this moment, but I would love to pay and have everything work well.