It is either in the download folder in the creator. I also had issue with things from the Workshop showing up in single player. Once I switched to multiplayer hosting my own private server everything showed up just fine.

I don't get this.

I've DL'd some iso from within the game, and they work fine.
But i cannot find the Subbed iso's (there's more in the workshop than are in the in-game browser)

The ingame stuff is in download folder in the creator.

But the subbed stuff is nowhere to be found.

I think this may still be an issue. I think it depends on when the ISO was uploaded to the Steam Workshop. Older files won't work because they are the wrong file format (not .vciso) so they won't show up in game. I think that I have successfully subscribed to a few items, so I think at least a few things can be subscribed to and show up in game. That makes me think that newer files may now be stored as the correct file type. Unfortunately, I don't think anything can be done with older files, even if you change the file extension I don't think they will load properly as ISOs.

EDIT: the in-game workshop is a different workshop from the Steam Workshop. Some files were originally loaded to both by the authors, and the in-game files work fine for download. As I said, some of the Steam subscription files will download into the game, and others will not, as far as I can tell.

Now, I know this one is old, but there is no newer one it seems. So, with www.planet-explorers-isos.com seemingly not working, and Workshop broken, does anyone happen to know a place where people actually share their ISOs (beside Nexus and in-game ISO section)?