Is this a bug in Lectora?

When formatting text, the the order of the text in the box often moves!

For example. I have a text box with two paragraphs of text.

I highlight paragraph 1 as I want it to be a larger font. I select the text, select the text size from the drop down

and next thing the paragraph of text moves to below what was originally paragraph 2!

Has anyone else noticed this and is it a known bug that is on an enhancement list somewhere?