Are GuiButtons block Mouse.Up/Down connections?

Help and Feedback Scripting Support
#1

Hello guys. I’m trying to make drag-n-drop system for my inventory and hotbar system. But, when I start dragging, script somewhy unable to detect, when I releaze mouse button. But, while drag script had error which shifts it 36 pixels above (GuiInset size). So, this lead me to question: does GuiButtons block mouse connections?
(Script:)

local DragSlot, ActiveDrag, ActiveUp, ActiveSlot
local function SlotHold(StartX, StartY, Slot, Active)
	if Active == true then
		print("Drag started") <-- cfn be started by holding on button.
		ActiveSlot = Slot
		local MouseOffset = UDim2.new(0, StartX - Slot.AbsolutePosition.X, 0, StartY - Slot.AbsolutePosition.Y - 36)
		DragSlot = Slot:Clone()
		Slot.Visible = false
		DragSlot.Size = UDim2.new(0, Slot.AbsoluteSize.X, 0, Slot.AbsoluteSize.Y) --bc I use scale inside scrolling frame, and I need persistant slot size.
		DragSlot.Position = UDim2.new(0, StartX, 0, StartY) - MouseOffset
		DragSlot.Parent = GuiSections.Inventory
		ActiveDrag = Mouse.Move:Connect(function()
			StartX = Mouse.X
			StartY = Mouse.Y
			DragSlot.Position = UDim2.new(0, StartX, 0, StartY + 36) - MouseOffset
		end)
		ActiveUp = Mouse.Button1Up:Connect(function()
			StartX = Mouse.X
			StartY = Mouse.Y
			SlotHold(StartX, StartY + 36, nil, false)
		end)
	else
		print("Drag ended") <-- this can be fired only if mouse released, but it never gets fired after I fixed 36 pixel bug.
		if ActiveDrag then
			ActiveDrag:Disconnect()
			ActiveDrag = nil
			ActiveUp:Disconnect()
			ActiveUp = nil
		end
		local Success
		for i = 1, #GUIforHoverTest, 1 do
			local SlotStartPos = GUIforHoverTest[i].AbsolutePosition - 36
			local SlotEndPos = SlotStartPos + GUIforHoverTest[i].AbsoluteSize
			if SlotStartPos.X <= StartX and SlotEndPos.X >= StartX and SlotStartPos.Y <= StartY and SlotEndPos.Y >= StartY then
				Success = i
				break
			end
		end
		if Success then
			local HoverSlot = GUIforHoverTest[Success]
			local SlotType = HoverSlot:GetAttribute("Type")
			if SlotType == "Hotbar" then
				print("Moving item into " .. tostring(HoverSlot.Name))
				self:MoveToHotbar(ActiveSlot, string.match(HoverSlot.Name, "%d+"))
			end
			ActiveSlot:Destroy()
		else
			ActiveSlot.Visible = true
		end
		DragSlot:Destroy()
	end
end

Some images:
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(Holding pickaxe slot)

image
I reliazed mouse button, but no event fired!

image
Console