How to reproduce:
setxkbmap -rules evdev -model pc105 -layout us,gb -option -option grp:shifts_toggle
Testing the second symptom in a Windows 10 guest:
Run Windows 10 guest and go to Control Panel → Mouse and select either Pointers, Pointer Options, or Wheel tab and try to change values in the drop-down-menu (Scheme), list-box (Customize), slider (Select a pointer speed), or up-down value (the number of lines for vertical scrolling). The values will all change only up and they are changing even if the mouse pointer is just moving (while the particular setting is selected).