Wildcards shows instead of calculated formula in Writer

In a bulk letter I updated the connection to a data base.
After that there are only the wildcards in the letter instead of the referenced data base field entries.

The new data base is already shown in the “Data source”

However I cannot bring writer to update the wildcards…

Thanks for advice

Print it.
Confirm that you are going to print a serial letter.
Print to some file and see.

Thanks for the advice.
I tried to do that. But it is only printing one page with the visible wildcards like
It is also only one page long.