No matter the version, whether or not I keep the 'Fullscreen' addon enabled or disabled, I get this issue. I have had this issue with different monitors, different window resolutions, and it always does this.
#Fullscreen does not work properly
sweet sparrow
mighty pewter
Assuming your on windows the issue is your sizing settings found in Settings > System > Scale and layout which should be set to 100% but you likely got it set to 150% which causes full-screen to break, had the issue too recently and this was the fix for me