Did this the other day and it worked for me..

If you already have Core installed, to install Knots you should:

In the StartOS System tab, click the “Manage” heading 5+ times to enable developer mode.

Click “Reinstall” on Knots in the Community Registry.

If you get a notification claiming the install failed. Don’t worry, it succeeded. You just need to open Knots config and click “Save”.

Knots is now installed instead of Core. There no need to resync, and all dependent services should be happy.