Someone( @WhatThaFrank ) on this forum suggested this FIX, and it works:

Here's some useful steps that helped me get this feauture back:

1. Open: opera://flags/#scrollable-tab-strip in a new tab;
2. Go to where it says "Scrollable tab strip";
3. On the drop down menu to the right of it, click "enabled";
4. Hit the "reload button on the bottom right or if it doesn't show itself, RESTART your computer;
5. Fire up OperaGX, try it out and see if it works.

Enjoy your feature again like before!

Someone( @WhatThaFrank ) on this forum suggested this FIX, and it works:

Here's some useful steps that helped me get this feauture back:

1. Open: opera://flags/#scrollable-tab-strip in a new tab;
2. Go to where it says "Scrollable tab strip";
3. On the drop down menu to the right of it, click "enabled";
4. Hit the "reload button on the bottom right or if it doesn't show itself, RESTART your computer;
5. Fire up OperaGX, try it out and see if it works.

Enjoy your feature again like before!