Problemcreating spline waypoints

I’m having a problem creating spline waypoints whereby MP stops responding for 15 - 20 seconds before finally adding the waypoint with all zero values several thousand miles away.

i’ve been using MP for quite some time but never tried spline WP before. Upgrading to the latest version makes no difference.

I am using a Windows 10 tablet. I previously used a windows 10 laptop and have just tested the latest version of MP on that and spline waypoints appear to work fine.