Dedoimedo posted a fix for the Samba shares issue in Ubuntu 18.04
A quote from the article:
Microsoft Windows makes up the vast majority of desktop systems in the world. Easily 90%. This means that if you're testing Linux or considering dual-booting Windows and Linux, you will most likely have a Windows machine in your setup, and you will want to share files. Samba is the easiest way to do things. In your Linux box, in a file manager, in the address bar, type smb://, followed by a host name or IP address, and you should be able to connect to your Windows shares. Well, in Ubuntu 18.04, not so anymore.Ubuntu 18.04 - Samba shares problem fix
I've encountered this problem while testing Bionic Beta and then again when I took Kubuntu 18.04 for a spin. In both cases, I was not able to reach my Windows shares. Now, this is a stupid problem, because I can connect to Windows shares from EVERY other Linux system I have. Let me show you how you can fix this.