I have a Canon MG3600 series printer connected to local network by wifi.
And also, I have an Orangepi zero and a Raspi 3b which all burned with dietpi firmware.
I install CloudPrinter by dietpi-software in Orangepi zero, and install Cups by apt-get in Raspi 3B.
It is strange that Orangepi cann’t find Canon printer, but Raspi 3B can.
How can I fix it in Orangepi?
I gonna try my luck here 
On the Cups settings page https://:631/admin login with root/dietpi or your own set user/password.
Look unter Administration, the right table, check the box “SHow shared printer from other systems”.
(My system language is different, no guaranty for the right text 
)
I try to reproduce the behavior of your case. No luck till now, the checkbox always goes empty.