Someone that could explain the following situation or if it was a bug in windy?

A heavy shower (later thunderstorm) developed over Essex in England (just W of Ipswich). According to the steering level in 700hPa, they should move towards S (which they later also did) but according to the radar forecast 1h, they should move E. Was this a bug? I looked at other altitudes as well, and none at a reasonable altitude showed a propagation towards E. Also the hours before and after the current time showed a propagation towards S. Just S of the showers, we had a weak warm front moving S. About 30 minutes later, the radar forecast 1h showed a propagation towards S. So my question is, what is the the radar forecast 1h based on?

See images below (wind forecast at 700hPa):

Best Regards