Dynamic text box somehow became unselectable

I have a weird problem. In my Animate project (HTML5 canvas) I have one place where a dynamic text box became unselectable. The layer is unlocked, there's a dotted frame around the text box, but there's no way to select it. Clicking does nothing, dragging a selection box around it does nothing too. It's like the text box doesn't even exist.

I tried to attach the problematic file, but I got the error "The attachment's unselectable text.fla content type (application/octet-stream) does not match its file extension and has been removed." 😞