On a General Journal Batch, you can check the field Suggest Balancing Amount.
When this feature is enabled, the Document No. is no more auto-incremented when the balance reaches zero.

You can reproduce this behaviour by following theses steps:
1. Go to a General Journal
2. Open the General Journal Batch and check Suggest Balancing Amount
3. Type a first line with an Amount = 1,000
4. Type a second line, it will be filled with Amount = -1,000 automatically
5. Start a third line, the Document No. is still the same as before.

I think the expected behaviour would be to increment the Document No.
Needs Votes
Ideas Administrator

Thank you for this suggestion! Currently this is not on our roadmap. We are tracking this idea and if it gathers more votes and comments we will consider it in the future. 

Best regards, 
Business Central