Line spacing will not respond to single-click attempts to increase or decrease.
Attempting to simply increase or decrease the line spacing in a paragraph of text.
Clicking once to increase or decrease the line spacing in text panel does nothing; clicking multiple times eventually changes the line spacing in a paragraph.
This behaviour is not consistent across other documents.
The screen recording at the following link has been cropped to include the text paragraph and keep the top toolbar in view.
Software used to capture the screen does not include the floating text panel and i do not know why. However the changing line spacing values are visible in the top toolbar and illustrate the discrepancy between the changing line spacing values and the fact that the text itself does not change as the line spacing is being increased or decreased.

