I tried to select a text with an italic modifier, but selecting the text failed.
How I produced this in that particular message: With composer open, on desktop, I started selecting the text from the beginning of the paragraph above. I selected some text (cue first image) and while pressing the mouse key and moving it to the beginning of the second paragraph, the selection disappears. I continue selecting more and some text is selected (cue second image).
First image, some selecting on the first paragraph:
Second image, after moving over to next paragraph and continued selecting:
The condition is reproduced in incognito mode. Will provide link, if necessary.