If your goal progress isn't appearing correctly, the start value for your key result(s) is incorrect.
You can see your Goal Progress from the Goal Detail page:
If you see that the "Goal Progress" is listed as a negative number or any number that does not accurately reflect your progress on the goal, your start value for one or more of your key results is incorrect.
How to Reset your Start Value
To make your goal progress update correctly, you will need to correct your start value for one or more of your key results. To begin, click on the three dots next to the Key Result and click Edit Key Result.
The Start and Target values for your key result will now appear and will be editable from this view. The vast majority of the time, your key result starting value should be 0. If you see a value other than "0" listed as the start value, delete it and type in "0". Then click Done.
Update the Start Value to 0 (or whatever the correct start value for your particular key result is) and click Done.
Below is a quick gif illustrating how to complete the above steps:
How to Update your Progress on a Goal Correctly
When you update a goal, it's important to click the Update Goal button to update your progress on your goal's key results. Accidentally editing the key result start value instead of updating the goal to reflect current progress on your key result will cause your goal progress to go down.
Once you click Update Goal, the below window will appear. For every key result that you have made progress on, you will enter in the current progress on that key result.