I too am having the same problems as Dodge22 mentioned. After bringing up YouTube each time after doing one video. The icons, cover screens and descriptions start disappearing. Then the list of my subscriptions disappears and then everything but the red arrow at top left disappears. I have two different roku devices the stick and the express both less than two yrs old. I have deleted the YT app from both tvs, rebooted both tvs, then reinstalled the apps again to no avail. This is serious and seems to have started after they changed to the new format. Only way to work around is screen mirror from phone to TV and that only works on one of the tvs well. Please get this fixed as I only watch YouTube videos and no longer watch 'regular' TV.
Update: Wed, 4.17.2018 Seems better now. Haven't noticed it doing this problem so much. Maybe it was a glitch when switched the format from top down to sideways. Thanks for elevating it to youtube. Maybe that made a difference. If so, thank you, thank you!