We use Lexmark Laser Printer model CS820
Windows 10 OS

We use our indesign file as a template to print custom certificates.
We change the name on the certificate for each customer.
The printer will not print all elements of a design: i.e. the images and text are missing.

And

Files will often not print immediately but will 'sit' in the printer memory for up to several minutes before printing.

For a print business this is not acceptable. Please advise with working solutions.

We have a Lexmark CS827 and this works fine.