AutoCAD 2018 MEP Batch loading & updating attributes in Title Block AutoLisp

Question

I have a Autolisp program as defined below it works very well. Essentially the program open drawings in a selected folder and opens each drawing in turn updating the attributes in the Title Block. And all that works well. The problem I have is when the drawing loads, I get a white screen I can't see my title block in paper space as I should. As the drawings load into AutoCAD 2018 MEP I intermittently see a title block in paper space and then when the next drawing loads again I see a white screen in paper space.

Any Ideas on this? Any help much appreciated. Perhaps some veteran AutoCAD 2018 MEP users might have some ideas.

(defun c:A1TB(/ filepath dir n tfiles)


    ;;Prompt the user to select a folder containing drawings
    (if (setq filepath (getfiled "Select a Drawing File..." "" "dwg" 16))
        (progn
                ;;Grab the directory only from the selected path. Remove the selected filename
                (setq dir (VL-FILENAME-DIRECTORY  filepath))
                
                ;;Create a list of all the drawings from the above selected folder
                (setq tfiles (vl-directory-files dir "*.dwg" 1))
                
                ;;Retrieve the current value of cmdecho
                (setq oldcmd (getvar "cmdecho"))
                ;;Turn off the command echo
                (setvar "cmdecho" 0)
                ;;Retrieve the current value of lispinit
                (setq oldinit (getvar "lispinit"))
                ;;Retrieve the current value of SDI Single Document Interface
                (setq oldSDI (getvar "SDI"))
                ;;Set SDI to 0 Single Document Interface
                (setvar "SDI" 0)
                ;;lispinit 0 = AutoLISP functions and variables are preserved from drawing to drawing
                (setvar "LISPINIT" 0)
                
                
                
                (setq n 0) ;;Initialise our n counter variable to 0 this variable is used to step through our drawing list
                
                    ;;Iterate through all the drawing in the selected folder. Open each drawing in turn one by one, and update the attributes
                    (while (< n (length tfiles))
                        ;;Open the nth drawing in the list for processing
                        (command "_.fileopen" (strcat dir "\\" (nth n tfiles)))
                        ;;Switch to Paperspace
                        (command "_.tilemode" 0)
                        ;;Zoom extents on the drawing
                        (command "_.zoom" "e")
                        (tb) ;;Update our attributes in the drawing title block. Moving across each tab and updating each title block as necessary
                        ;;Save our drawing after updating the attributes
                        (command "_.qsave")
                        ;;Increment our n variable, prepare to load the next drawing in from our drawing list tfiles
                        (setq n (+ 1 n))                        
                    );;End While
                
                
                    ;;Reset command echo
                    (setvar "cmdecho" oldcmd)
                    ;;Reset LISPINIT
                    (setvar "lispinit" oldinit)
                    ;;Reset SDI
                    (setvar "SDI" oldSDI)
                    
                    ;;Notify the user how many drawings were processed
                    (alert (strcat "A1TB Command Complete " (itoa n) " drawings opened"))
                    (princ)
                    
        )
        (progn
                ;;If the dialog for selecting the drawings was cancelled, Notify the user.
                (alert "\nA1TB command was cancelled...")
                (princ)
        )
    )
)

I was going to try GRAPHICSCONFIG and turn it off or turn ANNOALLVISIBLE on and see if that helps. I wonder has it something to do with SDI on or off and LISPINIT