[Mayron]

This is because you have the Blizzard Raid Frames enabled to be shown while also using the Grid raid frames AddOn included in the UI Pack. You can choice which ones you want to use. If you want the Blizzard Raid frames then just disable Grid (or also uninstall it with all of its plugins). If you want to Hide the Blizzard riad frames then there is a side button on the left hand side of the screen, visible in the screen shot. Press that and blick the "Hide" button in the menu that pops up.

The reason the grid frames are blocking the target frame is because of an old bug with MayronUI Gen3 which is currently fixed in Gen4 (coming soon). All the unit frames in the screen shot are too high! To fix this go into "/suf"(shadowed unit frame settings) and go into the Unit Configuration list down to "Target of Target". All other unit frames are anchored to this so by altering this unit frame's Y offset you will also move all the others. Lower this frames Y Offset till everything looks correct. It will be in the "Frames" menu by clicking on the Frames tab at the top. Then I would also recommend pressing the Expand / Retract button to expand and retract it (or retract and expand it) so that the new position is saved in the MayronUI database.