I'm having this problem. Initially it looked exactly like that as in the OP. I uninstalled all drivers (with DDU), and reinstalled them (with AMD's own utility), and now playback, timeline and thumbnails are all green:
I tried several decode option combinations, to no avail.
I'm on a Lenovo Ideapad with AMD Ryzen 5 4500U and Radeon Graphics, 2375 Mhz and DR17.
UPDATE: Now DR shows the video image in the timeline and playback window but doesn't playback. Not sure what changed underneath for that.