Grab viewport preview animation repetedly writing the same frame


Has anyone else encountered this problem? Max 2019 but I recall maybe 2018 as well.

I am trying to grab a basic preview animation PNG sequence of the viewport so I can out together an animatic… but all that is happening is Max is writing the same frame 100 times.

This is not the first time this has happened, and I think happening across two version.

Ring any bells?