Settlement defence bug

So I’m in the Slog building defences. I built 4 of the 8🛡️ turrets but the defences showed up as 40. I thought that was odd cos there isn’t already defence there. I googled it and it wasn’t the exact issue I’m having but it said to rebuild defences to reset it or something so I removed all 4 turrets and rebuilt them now the defence is stuck on 8 and won’t increase 🙃. Google and Reddit have no answers to this exact issue

It also said that each settler counts as 0.5 defence which can’t be true cos if you have no turrets it’s 0