This has been an off and on problem for me with Unreal 5.
[What is so frustrating is if you spam ctrl+shift+t enough the toolbar is shown nice and great for a split second before it flickers away and collapses to what it thinks is a better collapsed view, instead of where those toolbar buttons fit nice and should be…]
I feel like I’ve seen it often, because I move my computer around a bit to different displays. So on a tv (monitor), I had the issue, and I set the application scale (edit => editor preferences => appearance => application scale) to near minimum to see the right side of the toolbar… Expanding the viewport over the details panel will also get that part to show (unreal 5.5.4) 
