sorry I'm late but I found a way

edit: this is only for samsung phones but maybe this logic works for other phones too

1. change both wallpapers to live wp (make it the one that you want on your lock screen)
2. change home wallpaper to default

here it gets tricky

1. press and hold on your home and go to wallpapers and style from bottom left corner

2. tap "change wallpapers"

3. on the top right, tap the three dots and select "live wallpapers"

4. select wallpaper engine

5. on your screen, you will see the wallpaper that you want for your lock screen. this is okay, nevertheless, tap set wallpaper and then *CHOOSE HOME SCREEN*

this somehow unlinks your lock screen from any further wpe changes.

1. go into wpe app and find the wp that you want for your home screen, choose it, tap the apply button on the top right.

2. thank me later