WoWInterface - BfA - Bug with ScanTooltip:SetHyperlink?

I have code that checks the spell book on aura changed or spell book changed events.
I use ScanTooltip:SetHyperlink(format('spell:%s', SpellID))
This works the first time, but later ScanTooltip:NumLines() returns 0.
This works on live with no issues. So either a bug or something was changed?

The code that makes ScanTooltip

Code:

local function CreateScanTooltip()

  if ScanTooltip == nil then

    ScanTooltip = CreateFrame('GameTooltip')



    ScanTooltip:SetOwner(UIParent, 'ANCHOR_NONE')

    for Index = 1, 8 do

      local Left = ScanTooltip:CreateFontString()

      local Right = ScanTooltip:CreateFontString()

      ScanTooltip['L' .. Index] = Left

      ScanTooltip['R' .. Index] = Right



      ScanTooltip:AddFontStrings(Left, Right)

    end

  end

end