When attempting to have two separate numbered lists in succession, the two are combined into one and the numbers explicitly written by the user are overridden and replaced with ones in numerical order.
Interestingly, although this can be worked around by using <br> (which is unituitive for most users), using <br> in the bug report wizard is not a viable workaround. Additionally, adding a single line break via the enter key has no effect, but adding two does. Once again, the bug report wizard does not share this behavior, and the number of line breaks is irrelevant.
Create a numbered list (this)
Add some numbers
Attempt to have a separate numbered list directly below it starting from 1
This issue is still a bug within the bug report wizard in that case. <br> and the enter key do not share the same behavior between the bug report wizard and normal posting when distinguishing two lists.
You can add a text line between the lists to work around that or just edit it after posting. This case does not seem frequent enough to consider making changes to core markdown rendering across the forum.