Hi, thanks for sharing this bug here. These forums are where you can see if other players have had the same problem, or found a workaround to it.
To report the bug to Larian, you can use their support website. The "Report a Bug" link along the top of the launcher will take you to the right place.
(On the topic of workarounds, does respeccing with Withers help? I have no idea what happens with spells memorised from scrolls if we do that, so it's a bit of a long shot I admit.)
