What is happening:
Exclamation mark is shown over Parsley even if the quest is marked as completed and characted graduated. It was already reported and it's been said there is a fix with Old Quest Marker Fix (ticket here: http://phabricator.legendsofequestria.com/T2551 - all options provided by Old Quest Marker Fix are listed there in last comment) but that option does not show up. When talking to Parsley there is no option about the quest any more.
What should be happening:
The option for The Magic of Ordinary Neighs should be shown among the conversation options with Old Quest Marker Fix.
Steps to reproduce the issue:
There was probably game crash involved while the quest was active, but it's long time ago, so not sure.
This is how the quest looks in journal: https://imgur.com/ifiaaU0 (the whole quest completed, but the subtask with Parsley stil seem to be active).