Hi @Bunnz75. How long has this been occurring for? If you perform a Soft Reset, are you then able to unlock your Tab? To do this, hold the 'Power' button and the 'Volume Down' button, both together for ten seconds and it will restart (don't worry, nothing is deleted by doing this).
Thank you for your assistance. However, there seems to be a problem with the actual drawing of the pattern itself. only a part of the pattern displays and the message "try in 29 seconds" still appears. I know it is the correct pattern, because it has been in use since I bought the tablet in 2019.