Pages image caption text box won't approach document midline
I am using Pages for a bi-monthly newsletter (Mac Studio, OS Tahoe 26.6.2, Pages 15.3.1). The document is set to one column, but I manually create two columns, so as to have greater layout flexibility. The caption for one image in the right column refuses to approach the document midline beyond a certain point. If I move its text box leftward toward the center line, the caption text retreats to the right inside the text box, maintaining its position in the document. What control feature is governing this behavior?
Mac Studio, macOS 26.6