See the attached images for examples.
When clicking on the "Filtered by" drop down on Ubuntu Desktop Client, the filter options show up on the second screen in a dual-screen setup.
Which version of Spotify do you run?
What version of Ubuntu do you run?
Does it happen in other filter views except for podcasts? Like Albums, Artists?
I can recreate the problem on one screen by just dragging the window aside without resizing it. If I resize the window, the dropdown is in the correct place again.
Here's the info you requested.
(python-2.7.13) andrew@trekt:~$ cat /etc/os-release
VERSION="16.04.4 LTS (Xenial Xerus)"
PRETTY_NAME="Ubuntu 16.04.4 LTS"
(python-2.7.13) andrew@trekt:~$ spotify --version
Spotify version 1.0.**bleep**.336.g7edcc575, Copyright (c) 2017, Spotify Ltd
I hadn't ever tried anything besides podcasts, but it looks like you were able to reproduce this with Albums.