Reproduction steps:
1) Open user submitted project, proceed to main scene and notice messed up UI.
2) Expand canvas and select "scrollview" object, either revert prefab or edit any Scroll Rect components value.

Note: Going into playmode also fixes this issue.

Images for both results included below.
Epxected result: UI should have been ok from the get go.
Actual result: Step 2 required to fix UI.

Workaround: Reproduction step 2.