SVG2 Text Unflow has no effect

Steps to reproduce:

• New document
• create rectangle
• create text object with single long line of text
• select rectangle&text object
• Text|Flow into Frame => as expected, text line is broken up to fit into rectangle
• select Text and/or rectangle
• Text|Unflow => no effect whatsoever

In fact, I could find no way to break up the link between the text and the rectangle. Even Copy/Cut/Paste/Duplicate of either the text and/or the rectangle in various combinations does not allow me to create a text that is not flowed to the same original rectangle.

What happened?

Could not find any way to unflow the text.

What should have happened?

Return the text object to its original single-line state, breaking its ties to the rectangle

Inkscape Version and Operating System:

• Inkscape Version: 1.0beta2
• Operating System: Windows 10 Enterprise
• Operating System version: 1909 (build 18363.535)