According to the inkscape forum:
Flowed text is created
- when dragging a frame with the text tool before entering the text.
- when flowing text into a frame (menu 'Text > Flow into Frame')
To convert flowed text into regular text, save a copy of the file and
use the menu command 'Text > Convert to text' in the copy (to be able
to edit the flowed text later on in the original if needed
I have confirmed the convert to text works - just make sure you select the text and not a frame for example.
Note that some software, such as Apache's Batik SVG Toolkit, cannot render SVG with
flowRoot elements. Consequently, any software that uses the Batik library (such as JasperReports) will also be unable to display the SVG file. The error message from Batik will include a short description about
flowRoot being the cause of its inability to render the SVG file. Converting the text to text, as described above, should alleviate this issue.