Following the tutorial here for using Order Tags to apply discounts, you can not remove the discount by selecting the Automation Command Button again.
The only way to rectify this is to untick Add Tag Price To Order Price in the Order Tag Discount.
John I think the problem occurred after we solved this issue 
I can’t remember the reason for that behaviour either, but I will work on it with Update Order Tag instead.
Hi John and Emre,
I have posted another issue before multiple searches through the forum revealed this thread.
I have a similar issue. Orders when applied the 50% discount cannot revert back to original price if I turn off the 50% Discount Automation button.
John you seem to indicate a workaround with Update Order Tag, how would I do this please?
Thanks
As stated in the first post. It happens due to adding order tag prices to the main product.
Thanks for the clarification John, so I take it this is still an unresolved problem?.
The reason why I say this is because it used to work perfectly on V3. I was the person whom asked for this feature on the 50% discount initially and Emre was kind enough to show me the light on V3.
Given that it used to work in V3, I am suprised it behaves differently in V4. Regardless it is a small problem that I am happy to live with. Thanks again for your clarification.
At this point in time we need to not compare V3 with V4. V3 is in a feature freeze as @emre is the only developer, and his focus has been on V4. Which has left no time to bring V3 up to the same level as V4.
So V4 has new features not available in V3.
The problem is technically not an issue as changes have been made to Order Tags and Update Order action to accommodate newer features and this behaviour with the 50% discount setup is a side affect. While it is an annoyance to so small level, it’s far from a show stopper.
And as you know, there is more than one way to do something in SambaPOS 