Probably the first two things to check are that you've only got the one version of Wolfram Mathematica installed and that it's also the latest version.
If the problem still persists after you've double-checked the above, you can also choose to reset and restart the Dock. Note you will need to re-add any non-default icons (i.e. apps) that you've added to the Dock - so you may want to take a screenshot of your Dock as a reminder of what you had there. (Or start afresh and only add things as you actually use them).
To reset and restart the Dock, follow these steps:
- Go to Finder
- Press and hold the option key down
- Now go to the Go menu
- Select the Library option to open the User's Library folder. You can let go of the option key now.
- Go to the Preferences folder (i.e. within the Library folder)
- Find and move the com.apple.dock.plist file to the Trash
- Now open Terminal (usually located in Applications > Utilities)
- Enter this command
killall -KILL Dock
- Press enter
As mentioned previously, you will need to re-add non-default apps back to the Dock.
If this doesn't resolve the issue, it's almost certainly an isolated issue with this app and you'd be best to contact their support to raise the issue with them.