Comet spell often fails to cast

I've been using the comet spell a lot recently (self cast), and have come across many cases where the spell fails to cast.
The whole casting animation plays, the full mana cost is paid, and then... nothing happens.
This is really bad, as comet is already punishing to self cast with a long cast time where you're stuck in place, and a high mana cost, and can be interrupted during the cast.

It seems as if the game checks if you have line of sight to the target at the very end of the casting sequence, and then just fails if you don't.
My reasoning being that this problem happens much more often in areas with a lot of walls and doorways.
When using the unleash support there are also cases where only the original cast succeeds, and the repeats fail.

In most of the cases where the spell fails, the character hasn't moved during the cast, so this isn't just a case of being pushed around or attacked by monsters.
That said, I've also had plenty of cases where the jump back mechanic seems to have taken me out of line of sight, causing the spell to fail.

Speaking of the jump back mechanic, it also seems to trigger a lot at long range as well, not only when targeting close to the character.

Bumping this, as it's still an issue in the current version.
Not being able to move while casting and having an unscalable added cast time makes self-casting comet pretty useless in the end-game, and these bugs make it even worse

Detonate dead has the same problem, it fails to cast in narrow spaces while spending your mana, so frustrating.

There are a few crossbow jammed reports. Could be the same issue.