Cannot mark active; Same error every time

There are times where I'm not active on my computer but I'm actively working away from the keyboard. I used to be able to mark these gaps as active. However, now when I try to mark these gaps in my activity as active, I consistently get an error that no idle activity was found to mark active. I don't understand what "idle activity" it's trying to find and what gets designated as "idle activity". I should be able to mark time as active without any conditions. If there's a programmed definition for what time can be marked active, that should be an organization setting. I could understand why organizations may be more specific about what gaps can be marked active, but as a personal user, I don't want to be restricted based off some accountability functionality and HR definition of what can be marked active.

Also, I've tried adding a time entry to fill the gap and it doesn't mark it as active and I still get the error when I try to "Mark Active" by selecting the gap in the activity column.