Thank you for contacting the Community with your concerns regarding editing budgets. I can help share some update about this issue you're seeing.
There are reports about unable to enter amounts into budgets without holding down the left mouse button. Our Engineering Team is aware of this and is diligently working to resolve this in a timely manner.
For now, you can right click on your mouse while you type, this allows you to enter data in your budget. You can also right click on the row you want to edit and then click in the cell you need to enter data.
Also, please contact the Customer Support Team so they can pull up your account in a safe environment and sign you up to receive email updates as soon as they become available. Rest assured, I'll keep an eye out for updates and provide them as soon as they're made available to me.
Thank you for your patience as we work through this issue. If you have any other questions, please don't hesitate to reach out to me again. I look forward to hearing from you again.