Thanks for posting your question here.
I reviewed your more recent listing attempt which generated this warning and it appears this occurred because this value is now labeled “High (3 in. and Up)” instead of “High (3" and up)". This very well may have been a result of a recent eBay change, although I was not aware of it previously.
As such, I believe all you will need to do in order to ensure your “Heel Height” value is submitted to eBay successfully with this listing is change the value which is currently selected to the similar option called “High (3 in. and Up)” which is now available in this field.
I hope this clears things up.