The "reporting functions" in expression builder were always empty.
Another bug?

please check it, thanks.

I haven't understood the bug that you pointed out. Can you please give me more information on this bug and steps to reproduce it.

For example:
Add a table to the report, and insert a data field.
Double click on the report item will popup the dialog "Edit Data Binding".
Click the fx... icon of the "Expression:" textbox.
There are 3 textarea below:
Category, Sub-Category, Double Click to Insert.

There are some items in the Category:
Available Data Sets, Available Column Binding, Report Parameters,
Native Javascript Functions, Reporting Functions, Operators

Select "Reporting Functions" in the Category, the Sub-Category is always empty.
I remembered that it should have "Finance Function" etc. options in the 7.0 M2.
Now it's all gone, just empty.

Thanks for posting these detailed steps. We were able to replicate this issue. I have filed a PR and we will try to get this resolved asap.