If you upgrade to Mac OS to 10.15 (Catalina) or OSX 11 (Big Sur), due to the change in OSX security policy, you need to answer a prompt from OSX system to allow Worksnaps client to capture screen. Without the permission from you, only the background of your screen will be captured (i.e., no application window will be captured.)
Here is what will happen:
1. After you launch Worksnaps Client, when it tries to capture screen notification for the first time, there will be a Screen Recording prompt from OSX (see below). You can click Open System Preferences button to grant permission.
2. You will see the following dialog box
(Note: If in step 1 you click Deny button, you can still manually open System Preferences -> Security & Privacy to perform this step.)
3. Select Screen Recording on the left navigate and check the checkbox for Worksnaps Client on the right to grant it permission to capture screen.
4. Now you will see another prompt as below. Please click "Later" button then Worksnaps Client will be able to capture screen. (Although the message says Worksnaps Client will not be able to record the contents of your screen until it is quit, it is not true. You do not have to quit it by clicking "Quit Now". So, simply click "Later" will make it work.)
5. You need to enable Accessibility for Worksnaps Client also, Privacy
(If you have enabled webcam capture in Worksnaps Client, please read on)
6. If you enabled webcam in Worksnaps client. It will prompt the camera access permission prompt dialog at the first time Worksnaps Client tries to capture webcam. You need to click OK button.
7. If you click "Don't Allow", you can open System Preferences -> Security & Privacy -> Camera to enable it. Once this is done, the web cam image can be captured by Worksnaps Client program.