Shutter screenshot application is broken since upgrade to Ubuntu 21.04 Hirsute Hippo

Since upgrading to 21.04, the Shutter screenshot tool stopped working.
I installed it from the PPA http://ppa.launchpad.net/linuxuprising/shutter/ubuntu, it is at Version 0.95, Rev.1450

Let’s say, I start in this configuration:
Starting setup

When I now try to screenshot a selection, instead of showing the screen contents, it tiles it’s own window content:
Tiled window content

I would assume this has something to do with permissions, since the Window dropdown list is empty. Trying to capture the whole desktop yields an error message Keyboard could not be grabbed.

I already tried re-installing it via apt purge. There are no matching issues on Shutter’s Github page.

Any ideas on how to fix this?