This seems to be the same bug as these:
However both posts didn't provide repro and while I left a comment on the first post it makes more sense to create a new post so that it's not buried.
Peek version: 1.1.5
Unity versions tested: 2018.4.13f1, 2019.2.15f1, 2019.3.0f1
Steps to reproduce
0. create a fresh project in Unity and install Peek only.
1. add either an existing script or create a new script component to a game object.
2. editor thinks for a bit and then adds script icon to game object toolbar.
3. hit play -- you can still see the script icon in the game object toolbar.
4. stop play -- script icon disappears.
5. hit play again -- icon reappears.
6. hit stop again -- icon disappears.
So it looks like the icon is added to the toolbar after you add a script but disappears on exiting play mode.
Happens with a simple cube and a new behaviour script.
Also happens if you create an object that comes with scripts already attached, e.g. MapMagic -- it creates a new MapMagic object with a MapMagic script component, and the script icon that appears after creation disappears when you exit play mode.
Same result whether in maximised or standard layout. Same result whether script created by + icon on game object toolbar in the scene tab or via the add component button in the inspector tab.
Best guess is that the refresh that happens after first adding a script which makes the icon appear, and which also makes it appear during play mode, isn't being run again after play mode finishes.
Also noticed it hides the script icon(s) for the item in the inspector when not maximised. As above, icon is there to start with, then you hit play and it's still there, but you exit play and it disappears and then reappears only in play mode.
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