Thank you so much for bringing this issue to my attention, and than you for the great videos that helped me to clearly see the issue you were having.
Unfortunately, I was unable to replicate the issue you had. I’m not sure if maybe my test was slightly different than yours or if something was weird about your data. For example, I wonder if you maybe created those replies in a different order and then changed the dates on them later?
Anyway, even without being able to replicate the issue, I did see an area of the code that could possibly be the culprit. I explicitly set order by date ASC as a tertiary orderby.
Please update your plugin to version 2.1.3 and let me know if that solved the problem for you. Thanks.