I have done a lot of playing in the database and haven't been able to do this. It has been discussed before. Have a look at
https://www.mobileread.com/forums/sho....php?p=2590537,
https://www.mobileread.com/forums/sho....php?p=2510884 and
https://www.mobileread.com/forums/sho....php?p=2549948. They should give you some starting points.
There is something different in the latest firmware, but I haven't sat down to work out exactly what.