I've just encountered the vanishing lens bug. Had this in my previous game too, but didn't notice when exactly it happened. Now I have the exact turn. I was able to pin this down to when the Mont St. Michel wonder is placed on a tile, which requires to be built upon a march. Maybe this somehow screws with the logic when to display the lens. It only happens the turn after you have placed the wonder though. I can't remember if I've built the wonder in the last game it happened, too, or if some AI did it. // Edit Error message in the LUA.log file Code: MinimapPanel: Checking wonder 60 if ancient or classical Runtime Error: bad argument #1 to 'lMakeHash' (string expected, got nil) stack traceback: [C]: in function 'lMakeHash' C:\Users\xxx\Documents\My Games\Sid Meier's Civilization VI\Mods\More Lenses\UI\MinimapPanel.lua:814: in function 'isAncientClassicalWonder' C:\Users\xxx\Documents\My Games\Sid Meier's Civilization VI\Mods\More Lenses\UI\MinimapPanel.lua:592: in function 'SetBuilderLensHexes' C:\Users\xxx\Documents\My Games\Sid Meier's Civilization VI\Mods\More Lenses\UI\MinimapPanel.lua:923: in function 'OnUnitSelectionChanged' [C]: in function 'func' [C]: in function '(anonymous)' ModalLensPanel: currentModdedLensOn = 0 // Edit 2 Fixed it by editing line 814 in MinimapPanel.lua accordingly: Code: -- Make hash, and get era if row.PrereqTech ~= nil then prereqTechHash = DB.MakeHash(row.PrereqTech); eraType = GameInfo.Technologies[prereqTechHash].EraType; elseif row.PrereqCivic ~= nil then prereqCivicHash = DB.MakeHash(row.PrereqCivic); eraType = GameInfo.Civics[prereqCivicHash].EraType; end I actually have no idea why you're checking for era of a wonder, but if this wonder has no PrereqTech, as Mont St. Michel does, and instead only a PrereqCivic, the function bugs out. This fixes it, and the builder lens is working fine again.