Howdy!
I have PopClip set to pop up below my cursor… and it is reliable, EXCEPT when I select a paragraph of text from bottom-most text to top (which I apparently do more often than selecting a paragraph from top-most text to bottom).
If I drag my cursor from the bottom of a paragraph to the top, PopClip will then pop up above the cursor… which is not what I expect.
I’ll record my screen for you if you’d like…
I should add that this is in every build I’ve installed so far, including 6073.
I never noticed, but same thing happens with my PopClip. A bug or a feature?
This is the deliberate feature that has been hard coded into PopClip since the very beginning.
The idea is that if you’re selecting vertically downwards, then you probably want PopClip to appear below the cursor so that (a) it doesn’t obscure the selected text and (b) your hand & eye motion naturally continues down to the pop-up.
Likewise, if you’re selecting vertically upwards, it appears above the cursor.
That is to say, with a vertical selection, it will ignore the setting you have for Below or Above.
However, if you’d prefer it to obey your position setting regardless, you can use the following user defaults key:
defaults write com.pilotmoon.popclip AlwaysRespectPositionSetting -bool YES
You’ve literally thought of everything! 
Thank you so much!