trying to reproduce the bug with a direct problem

DiffractionGratings/grating2D_data.geo

@@ -80,7 +80,7 @@ DefineConstant[
   h_pmltop                    = {lambda_max, Name StrCat[pp3, "0top PML size [nm]"] ,  ReadOnly 1, Highlight Str[colorro], ServerAction "Reset GetDP/T0, GetDP/R0, GetDP/Lambda_step, GetDP/total absorption"},
   h_pmlbot                    = {lambda_max, Name StrCat[pp3, "1bottom PML size [nm]"] ,  ReadOnly 1, Highlight Str[colorro], ServerAction "Reset GetDP/T0, GetDP/R0, GetDP/Lambda_step, GetDP/total absorption"},
   Flag_o2_interp              = {1         , Name StrCat[pp3, "2Second order interpolation?"] , Choices {0,1}, ServerAction "Reset GetDP/T0, GetDP/R0, GetDP/Lambda_step, GetDP/total absorption"},
-  Flag_o2_geom                = {1         , Name StrCat[pp3, "3Second order mesh?"] , Choices {0,1}, Visible 0, ServerAction "Reset GetDP/T0, GetDP/R0, GetDP/Lambda_step, GetDP/total absorption"},
+  Flag_o2_geom                = {1         , Name StrCat[pp3, "3Second order mesh?"] , Choices {0,1}, Visible 1, ServerAction "Reset GetDP/T0, GetDP/R0, GetDP/Lambda_step, GetDP/total absorption"},
   paramaille                  = {10 , Name StrCat[pp3, "4nb of mesh elements per wavelength [-]"   ] , ReadOnly 0, Highlight Str[colorpp], ServerAction "Reset GetDP/T0, GetDP/R0, GetDP/Lambda_step, GetDP/total absorption"},
   paramaille_scale_sub        = {1  , Name StrCat[pp3, "6Custom mesh parameters/refine substrate [-]"    ] , ReadOnly 0, Highlight Str[colorpp], Closed 1, ServerAction "Reset GetDP/T0, GetDP/R0, GetDP/Lambda_step, GetDP/total absorption"},
   paramaille_scale_layer_dep  = {1  , Name StrCat[pp3, "6Custom mesh parameters/refine deposit layer [-]"] , ReadOnly 0, Highlight Str[colorpp], Closed 1, ServerAction "Reset GetDP/T0, GetDP/R0, GetDP/Lambda_step, GetDP/total absorption"},