Switch tabs by mouse wheel in the tab bar ON TABS ONLY

[Admini]

1. Disabling theme does not help.
2. In Portable v4.3.9.238, the feature works as intended.
3. In 64-bit installer v4.3.9.238 (no addon enabled), with or without a Chrome theme, the bug persists.

For (3), it is not a clean install. I still need the bookmarks, browsing history, existing settings, etc. Since (2) is working well, maybe there are some conflicts with the USER DATA? Just my two cents.

Maybe you can try resetting your Settings in chrome://settings/reset
It will disable all your extensions but not delete them.