This is a known issue in Mendix 10.6:
It's only a visual bug, so you don't have to do anything with it currently. You can try the workaround if you like. Otherwise it should be fixed in a Mendix version.
I think the "not set" is a bug with the new microflow editor, which is fixed in later versions of Studio Pro
Do you get an error in your console? Or can you run your application? Otherwise, I think it would be a bug in Studio Pro.
See this forum post as well
https://community.mendix.com/link/space/microflows/questions/130693