I've checked and there was no visible default.xml, but when I was trying to copy newly created I was ask if I wanted to overwrite old default.xml.
Also I couldn't delete folder "custom_menu" so I've check the folder permissions - it was 357 (not sure, definitely 3xx). Setting permissions manually to 755 solved the problem and now I can create new entries.
OK, checked other server - same situation. Default permission is 341, changing to 755 resolves the problem
Also I couldn't delete folder "custom_menu" so I've check the folder permissions - it was 357 (not sure, definitely 3xx). Setting permissions manually to 755 solved the problem and now I can create new entries.
OK, checked other server - same situation. Default permission is 341, changing to 755 resolves the problem