I'm definitely seeing similar (mis)behavior when attempting to cast spells, with the spell book appearing to be stuck at the second page or so. You can indeed get around this by clicking page down and up, it seems clicking on show all spells works as well.

Super annoying. I would be fine not having this feature at all instead of what is currently implemented.

Oh, yes, but

Oh, yes, thus the "step in the right direction".

The reasons it's only a STEP is because

1) It only partly solves the issue of repetitive spellcasting. Having to open the spellbook, click cast, and then cast, is still 1 more step per casting than there should be. A quickbar would only have 2 steps.

2) It does little-to-nothing for the situation of wanting to cast a series of common choice spells in a row. You still have to open the spellbook each time (as with above), find the spell (which is not guaranteed to be on the same page as the last thing you cast), and cast it.

A strategic hotbar is a good call.

Also, this scrolling stickiness has been recognized and addressed by the devs.

I've often wondered why there isn't a permanent, stickied, "Known bugs/issues" thread on this forum. Would make it much easier for those reporting to ascertain whether something has been previously reported, and whether it is indeed a bug, or something else. The current system seems a bit disorganised to me.