I have a couple of the old multipurpose sensors that are showing up in the classic app, but not in the new one. Can I only have them in one or the other? I can see the sensor in the history of the new app, but it’s got an old sensor name, I renamed it when i moved it to a different room.
If you renamed it in the Classic app, you will most likely need to also rename it in the new app. There is a known issue about this 
I don’t have a way to rename in the new version as it doesn’t appear as a device at all.
contact ST support at https://support.smartthings.com
Yeah, I’m getting that. Super annoying, because adding devices seems to be kind of quirky for me in the new app, so I often end up resorting to the classic app for that, but then have to go back and fix the name in the new app. 