In new Ubuntu OS, the default Desktop session is Wayland. there is a possibility that you will encounter the issue that the captured screen image is a black screen.
Here are the solutions to deal with such issue.
Solution 1:
1. Launch Worksnaps Client using command line. You can open a Terminal, then execute commands:
cd ~/WSClient/
./run.sh
If your machine not installed gnome-screenshot command, you can install it with: sudo apt install gnome-screenshot.
This will start Worksnaps Client. You can log in using your account, select project/task, and start to log time. Please check whether screenshots can be captured normally.
2. If screenshots can be captured normally by using command line, the next time you can use the desktop shortcut to start Worksnaps Client (i.e., using the usual way), then the screenshots should be captured normally as well.
Solution 2: