Issue with Subsections in Grid Format Displayed as 'Orphaned Activities' in Moodle 4.5+

[studio-11]

Describe the bug
When using the Grid format in a Moodle course, attempting to create a subsection within an existing section results in the subsection title being displayed as "orphaned activities." Additionally, the following message appears:
"This section and its content are not part of the course structure and are not visible to students. To use any of this content, move it to a different section."
Even after trying to move content to a different section, the issue persists. The total number of sections that can be created is well above the number of sections currently in the course.
To Reproduce
Steps to reproduce the behaviour:

Go to a Moodle course configured with the Grid format.
Create a new section.
Attempt to create a subsection within this new section.
Observe the title and message of the subsection.

Expected behaviour
The subsection should display a user-defined title and behave like a standard part of the course, appearing properly within the course structure and being visible to students (unless hidden explicitly).
Screenshots
If applicable, add screenshots to help explain your problem.

Versions (please complete the following information):
Moodle: 4.5+
Format: Grid version 405.0.1
Browser: Chrome Version 131.0.6778.86

Additional context
The total number of possible sections in the course exceeds the number of sections currently created. This issue seems specific to the Grid format and does not occur in other course formats. Let me know if further logs or settings need to be shared.

[gjb2048]

@studio-11 Does the add subsection option look like this https://www.youtube.com/watch?v=Tqk3gjuAYHw ?

[studio-11]

yes it does. here is my video screenrecord : https://youtu.be/x4mlCDnyVgk

[gjb2048]

@studio-11 Thank you.

[gjb2048]

@studio-11 Fixed in development repository. Fix for M4.5 will be in the next release.