When in grouped state, last group is shown as if it was already unfolded

Bug Report

Steps to Reproduce:

1. Populate the table with some data
2. Add 2 columns to group by
3. Double click on the total
4. Notice last group having a minus sign before it

Expected Result:

Last group has a plus sign before it, and you have to click once to unfold it

Actual Result:

Last group has a minus sign, and you have to click twice to unfold it, as for every other subgroup if there are multiple.

Environment:

Version 2.5.1

Additional Context:

Screenshot from the example page: