My main difficulty is not being able to attach files from SharePoint libraries or Teams/Groups. It would be possible if only Asana would update to a newer version of the OneDrive file picker. It’s been requested here but hasn’t gotten any significant feedback from the Asana team. Office 365 seems to be pretty low on their priorities list compared to other competing web apps such as Wrike or Trello who have had this feature for some time.
Right now I make do with pasting SharePoint links into comments. It’s less than ideal.