Hi,
Please follow these steps:
1) open a course page in backend that already have any unit and section
2) now add another section, enter it's name and change section order (ex: put as first section).
3) Save and see where is the new added section.
On ALL my tests, there's no section created. The same occurs with units.
The solution is to add the section or unit without changing it's order.
Save. Load again and change order. Save again.
Yes, this is a known issue. The solution you shared is the only way as of now.
We are trying to fix this issue and will update you once it is fixed.