If it does not have LOS on the target it will move 50% of the distance and check again, if still no LOS it will move 50% and check again. There should be no LOs issues at all. Infact, thats one thing I spent a lot of time working on.
1. Just managed to reproduce the issue. It happens when the pet manages to run up "unclimbable" places, such as a bookshelf, a place with corrupted mesh or a steep hill.
As you mentioned the CC will try to move 50% of the distance to clear out the LOS issues(or atleast move closer), but is instead faced with a wall of "Could not generate path to xxx,yyy,zzz".
Don't have a log of it right now, since I am at work and didn't have time to post before i left, but I'll see about uploading one once i get back home.
2. As for the "run to mob and spin around it like a mad man" issue. I THINK this is starting with a LoS issue where the mob is rather close to the bot, then as the bot go THROUGH the mob it will attempt another "move to mob" event only to end up on the other side.
Saw this happen quite a few times when pulling mobs just on the other side of a tree(with no LoS).
3. Also had some strange issue where it would be close to finishing a mob off, but an add show up. Finish off first mob, send the pet to take care of add(when add was in melee range at first).
Pet would then proceed to run off with the mob(as in out of range).
Bot would then throw hunters mark and start spamming serpent sting, but not move into range - Leading to the bot just staying put, but the log getting spammed with "Mob >= my level casting serpent sting"(or something like that).
There was NO indication in the log that the bot was trying to move closer, since the mob in theory was in LOS, but just out of range("indication" as in "generated path from xx,yy,zz to xxx,yyy,zzz in nn seconds" or even a "failed to generate path").
Could be since this was after the initial pull, and it doesn't perform another "pull" once in combat?
Just a guess.
Either way, as I said above. At work atm so can't upload a log right now. Will try to get one up when i get back home.
Edit: added logs.
Yesterdays log split into 3 parts(due to size).
Am not 100% sure, but think logentries related to issue #1 is happening at around 01:58 on the 25th.
When it comes to #2 i do not have any time info on that as i forgot to check the time it happened, but it was happening quite frequently when pulling the various Wolves in hinterlands(last part of 25.07 and first few hour into 26.07).
And as for #3 i will have to see if i can reproduce that again, since i have no recolection of the time for that, except that it was when pulling one wolf and another one aggroed just as the first one died. I _think_ this was around 26.07 - 00:00 +/- 2 hours. But I'll just wait untill this happens again and take better note of the time.