https://invisioncommunity.com/forums/topic/467153-new-members-cannot-access-community-pages/?do=findComment&comment=2891274
https://invisioncommunity.com/forums/topic/466939-images-in-forum-posts-skewed/?do=findComment&comment=2890395
https://invisioncommunity.com/forums/topic/465824-achievements-adjusting-points-has-no-effect/?do=findComment&comment=2883296
Maybe change the placeholder from "Display Name" to "Display Name or email address", with a description under the field to explain which of either, or both, would be the item required there? As it stands now, people are just doing what they are told, then being advised some time afterwards that the information is incorrect.