Please note: time tracking field is not added to next-gen project configuration by default.
In order to avoid the issues when creating work logs for the next-gen project, please do the following.
Go to issue's page and click ellipsis (three dots) located at the top right corner of the screen.
Then, click Configure.
Drag the Time Tracking field from the right onto issue type fields, to the center.
Please repeat the same actions for all issue types present in the next-gen project.
By default, there are two issue types: task and epic.