Starting about a week ago I cannot add more than one control to a gallery. My dataverse environment is running authoring version 3.22022.31.
Steps to reproduce:
Insert a blank vertical gallery
Click the "Add an item from the Insert pane" link inside of the gallery
Add a label
Add a second label - This label will be added at the top level of the screen instead of being added to the gallery template.
Note that if I revert the authoring version to 3.22015.31 this problem does not exist.