Weather there are some Networks in Address List or not, in this dropdown there ist always the word "unknown" in the menu.
See in Attached Screenshot.

Just wanted to add the necessary information from normis, and red that only cli errors should be reported, so sorry,
see this as friendly reminder, i have overred that in first attemp.

When reporting an issue, please follow this template:

Version number (if the issue is upgrade related, specify which version was installed before as well);
-> Updated from 6.48.6 to 7rc.1 then all minor steps till rc5, error occured in every minor release
Router's model;
-> CCR1036
Steps to reproduce the issue;
-> Add new BGP peer and open output-network dialog on the tab
Configuration export (use '/export hide-sensitive' command);
->
Any additional information that would help troubleshoot the issue (screenshots, debug logs, etc.).

Thank you for the report, this is a winbox cosmetic issue, we will fix it in the next RC version.
Currently use CLI to set networks.

Same issue here but still no luck to solve and back downgrade the version from 7.1 to 6.49.2. my local prefix was not working advertised via BGP Network in version 6.49.2.

That tip should be added to the WIKI.
I searched for hours...

Same issue here but still no luck to solve and back downgrade the version from 7.1 to 6.49.2. my local prefix was not working advertised via BGP Network in version 6.49.2.

Probably you do not have an IGP route for your local prefix. In RouterOS v6 there was a synchronize option for BGP networks, where you could set synchronize=no or synchronize=yes. The option is now fixed to synchronize=yes and cannot be changed, so you won't advertise the prefix unless you have a local IGP route for that same prefix as well.

Dear Sir,

I have added a blackhole route also for my Public IP prefix but not worked.