StringRegExp crash on subject string length > 20154

I couldn't find any mention of this being a limitation so I'm asking to see if this is a bug. I have a script I use for remuxing videos and noticed AutoIt3.exe was crashing on some. I tracked it down to StringRegExp crashing when the subject string length was 20155 or more characters. It actually doesn't seem to crash 100% of the time when the string length exactly 20155 and doesn't work 100% of the time when its 20154, but does crash 100% when its say 20160 and always works when it's 20150 so it's a bit odd.

Anyways I attached a test text file and here is the code I was testing with as it might actually be the regex itself that's causing this.

FYI the code isn't actually suppose to find anything, later in the script I handle missing audio array.

$sInfo = StringLeft(FileRead(@ScriptDir & "\out.txt"), 20160)

$aAudio = StringRegExp($sInfo, '(?s)mkvmerge & mkvextract: (\d+)(?:.(?!A track))+Track type: audio(?:.(?!A track|Chapters))+Language: (\w+)', 3)