[Gameplay] Movement speed bug of homeguard boots

I was playing and upgraded my to . Then I saw my movement speed was 382 after the speed boost, but the movement speed was supposed to be 390. When I moved my mouse to my champ stat, it showed 0+382 instead of 345+45. This is my match history, hope it would help. http://matchhistory.na.leagueoflegends.com/en/#match-details/NA1/1568614997/35845717