This is the question I wrote in Japanese before.
Once again I will question in English. Excuse my poor English.
This problem comes up in "Doit.im for Windows".
I am using both Windows 7 and 10, and I found it under both circumstances.
When I create a daily plan, I can input the estimate time before editing tasks, but no data may not be entered after edited any of tasks.
This problem never occurs if I do not "edit" tasks.
I signed out and signed in again, but this could not be solved.
Furthermore, I uninstalled the app and re-installed and yet the result is still same.
Your answer is much appreciated and I expect some improvement in the program.