The Sheep and the Goats - sheep glitching, impossible to get the herd to Valentine

[WhyTheZorg]

I'm trying to complete the Sheep and the Goats mission and I fail every time at the point of herding the sheep to Valentine because the sheep keep glitching out of the herd.

 

Once the sheep are rounded up into the initial herd (on YouTube Videos, they basically stay more or less together after this) I chase/follow the herd at a sensible pace and distance, then some of the sheep dart/disappear/fly out in all directions really fast (less than a second to fly farther than minimap range), sometimes clipping under large rocks, sometimes flying high into the air and dying in a valley hundreds of meters off to the right... this happens about 2-3 times a minute until I run out of sheep before getting past the big mountain, and the mission ends in failure.

 

I'm fed up after my 6th try. Sick of buying the damn sniper rifle over and over, and the same conversation.

 

Anyone else see this (on PC)? Can I skip this mission and get to the next chapter?

[Darealbandicoot]

Fail 3 times and skip to next checkpoint 

[WhyTheZorg]

I was trying twice then quitting until the next day... now I see this on 3rd time in a row, thanks.