Create indented sub-numbered points in MS PowerPoint numbered lists

I'm well aware of that this question has been asked already, but none of answers provided don't work for me (including using tab etc.). Could this be connected with the slide master my company provides, that some functions are simply not available or overridden by others?

I've got a standard numbered list 1., 2., ... in a text box and would like to add a sub-numbered list to the first point being numbered with i), ii), iii) (see following screenshot):

What I'd like to achieve is this:

1. Terminal states:
    - {....}
    - {....}
    - {....}

2. ....
...

Alternatively, it could also be numbered instead of mere bullet points: What I'd like to achieve is this:

1. Terminal states:
    i) {....}
    ii) {....}
    iii) {....}

2. ....
...

As for my locally installed PowerPoint version, check out the following screenshot:

EDIT on intended solution using "increase list level":

I've tried what I was told, but for some reason the indentation does not happen. It's all aligned to the left border of the text-box, practically fully left-justified. How can I get rid of this issue?

Final edit:

I've found out that I'd introduced the issue from another PowerPoint presentation by copying one slide into mine. Then, when creating new slides, I unconsciously chose layouts from the other slide master and not from mine. This other slide master had the issue of "no indentation". So, beware of that in case you encounter yourself in a similar situation.

On my computer with Microsoft 365 apps (Version 2015, Current Channel) installed, I could create a second level via clicking "Increase List Level", typing the sub-numbered symbol and pressing "Tab".