Yeah, just happened to me again now, updated an Item to 1.2 and boom Taken Down.
Currently it looks like an Lottery for me, you know, you upload two binary identical Items one as Public and one as Unlisted
and then one gets Taken Down while the other is published or vice versa.
And then if you update them the Lottery starts over, will it by Taken Down or Published? Well, may the RNG-Gods be with you.
They also at least for me never ever provided any information why it happens, even after they manually review and then published
i never got any reason or instructions what was wrong.
Welcome to the Google Developer Dashboard Lottery... ;)