Im pretty sure this has been reported before since its hard to miss. But i could not find a bug report on this, so here we go:
If you set your editor to use small icons the curve editors icons disappear.
Hi , there is indeed a bug report in for this issue. The Jira ticket number is UE-7329. This issue has actually already been fixed internally and is planned to be integrated in a future build. I have started watching this issue and will get back to you with any changes that I see.
thanks for your patience,