"Invasion of the Phantom Legion" Bug Report - Unfinishable Main Story Quest

Consistent bug encountered mid-way through the solo scenario mission ‘Invasion of the Phantom Legion’ inside Elzowin’s Shade - Rothan - Rohendel.

I have progressed through the scenario until the mist comes in and I am able to defeat 46% of oncoming monsters and then I get an error message on the bottom stating “An unknown error has occurred. (140011)” and then no further monsters come.

I have tried exiting and re-entering the scenario but it gets stuck at the same point, the error message repeats itself when I run over a certain spot of terrain (screenshot for location reference: Imgur: The magic of the Internet).

Character: Veisha
Server: Moonkeep - EUW
Location: Elzowin’s Shade - Solo Scenario Questline ‘Invasion of the Phantom Legion’ (Rohendel)

edit: after a couple more tries this issue resolved itself, I am not sure what I did differently