Thanks for your reply. Here are the contents of the .bat file you requested. I'm assuming it is the "_" in the name that messed it up, as the original file was named "Comp 1", but the renaming algorithm added the "_4" (this was my fourth attempt, versions _2 and _3 also were previously generated by AfterEffects...)
cd\ cd "C:\Program Files\Adobe\Adobe After Effects CC 2018\Support Files\Scripts\ScriptUI Panels\GIFsquid\"
GIFsquidavi.bat 24 1500 "D:\Windows\Documents\WebWorks\Brittleknee\Gif Creation\1\Comp 1_4.avi" "D:\Windows\Documents\WebWorks\Brittleknee\Gif Creation\1\GIFsquid_Output" 0.5 480x "" "Comp 1_4.avi" false
exit