Tkinter widgets not fully loading

[nortski]

Can someone please help me troubleshoot this problem.
I have a top level window that asks a user to scan a RFID card and asks how long to activate the card for. Problem is, the window displays the buttons but they can not be pressed until the called function scanCardLoop has return a value. This is a problem as the close window button, and the window 'x' button can not be activated:

	def activateCard():

		#Instantiate a Toplevel window
		activateCardWindow = Toplevel()
		TopLevelWindow(activateCardWindow, 300, 300, "Activate Card")
		
		label = Label(activateCardWindow, text="Scan to activate:", height=0, width=100)
		label.pack(side='top')
		
		#Entry box for the returned value of the RFID card
		scancard = Entry(activateCardWindow)
		scancard.pack(side = TOP)
		
		#Buttons requesting how long to activate for
		hourBtn = Button(activateCardWindow, text="1 hour", width=20)
		halfDayBtn = Button(activateCardWindow, text="Half day", width=20)
		allDayBtn = Button(activateCardWindow, text="All day", width=20)
		allDayBtn.pack(side='bottom', pady=5)
		halfDayBtn.pack(side='bottom')
		hourBtn.pack(side='bottom', pady=5)
		
		#For some reason this update has to be called otherwise the calling root window will not load this window
		activateCardWindow.update()
		
		#Call the scanCardLoop and place the returned value into tagID
		tagID = scanCardLoop()
		
		#Please tagID into entry box
		scancard.insert(END, tagID)

	def scanCardLoop():
		waitingForScan = True
		
		while waitingForScan == True:
			# Scan for cards    
			(status,TagType) = MIFAREReader.MFRC522_Request(MIFAREReader.PICC_REQIDL)
			# If a card is found
			#if status == MIFAREReader.MI_OK:
				#print("Card detected")
			# Get the UID of the card
			(status,uid) = MIFAREReader.MFRC522_Anticoll()
			# If we have the UID, continue
			if status == MIFAREReader.MI_OK:
				# Store tag ID
				#global rftagID
				rftagID.set("%s,%s,%s,%s" % (uid[0], uid[1], uid[2], uid[3]))
				# Print UID
				print("Card read UID: %s,%s,%s,%s" % (uid[0], uid[1], uid[2], uid[3]))
				waitingForScan = False

		return rftagID.get()

I suspect that there is some update issue going on.