In VisualEditor, start a new line, write text "A", then enter the mathematical formula "x" (Insert/Math formula), then click into the document to make the Math formula popup go away, (you will notice at this point that no blinking cursor appears, the first symptom of the bug), then enter the text "B". You should now see "AxB" with "x" being a math formula and the cursor blinking behind the B. Now hit the cursor-left key once. You would expect the cursor to appear between x and B, but in fact it is invisible (bug). Hit cursor-left one more time: the cursor remains invisible (bug). Now enter "C". You should now see "AxCB" with the cursor blinking after the C. Now hit cursor-right: the cursor vanishes (bug). If you now move back with cursor-left to the formula x, you will see that the two positions with invisible cursor are not there anymore; the invisible position is now located between C and B.