It works properly when hovering over non-frozen columns: ![screen with the example][1]
Why does it happen? What information could help to debug the problem?
The same question on the 6pac/SlickGrid fork: https://github.com/6pac/SlickGrid/issues/528
UPD. Example: https://angular-empty-project-zoc3ab.stackblitz.io/ [1]: https://i.sstatic.net/DLZSP.png
Dont forget to include script "SlickGrid-2.4.29/lib/jquery.mousewheel.js" on your page.