The data is not shown in live version (only the data of the tables in the front-end)
I tried clearing cookies, incognito, different devices… nothing
It was totally fine till yesterday, when I added all the relations I needed.
In the builder and back-end tables everything looks fine. the relations are working there.
Okay, it’s as I suspected. You have a series of User Specific columns in your Suppliers table. I can tell they are user specific because of the blue coloured icon in the column header:
You almost certainly shouldn’t be using User Specific columns here. They way they work is that every user will see a different value in each row, and each row will initially be empty for every user.
You should delete those and recreate them as regular (not user specific) columns.