Update to the latest PDF24 Creator.
Test if tools work outside Toolbox.
Delete AppData\Local\PDF24\Toolbox cache folder.
Uninstall → reboot → reinstall as admin.
Check logs in AppData\Local\PDF24\log or Event Viewer.
Ensure antivirus/firewall isn’t blocking Toolbox.
If still broken, post logs + Windows version on the PDF24 forum.